Pseudopterosins and Seco -Pseudopterosins: Compilation and Revision of Conflicting NMR Data,Names,Numbering Systems and Structural Elucidation

Abstract

The present review is focussed on the structural elucidation of the bicyclic and tricyclic diterpenoid title compounds isolated from Pseudopterogorgia species, displaying a direct structural relationship with the biosynthetic precursor GGPP (regular isoprenoid skeletons). A compilation of ¹H and ¹³C NMR spectroscopic data is presented grouped by similar spin systems. Apparent inconsistencies or potential missassignments are discussed, pointing out convenient revisions of data assignment to improve structure correlations. Some hemisynthetic intermediates in the structural elucidation process are included, as well as data of representative synthetic compounds.

Keywords

terpenoids serrulatane NMR structural elucidation

Pseudopterosins A-D (PsA-PsD), tricyclic diterpene D-xylosides, were reported as new naturally occurring metabolites isolated from the gorgonian octocoral Pseudopterogorgia (now Antillogorgia) elisabethae with promising antiiinflammatory and analgesic activities.^1,2 seco-Pseudopterosins A-D (sPsA-sPsD), a related set of bicyclic arabinosides, were reported shortly after.³ The structures of the isolated compounds are shown in Figure 1.

Figure 1.

Structures of pseudopterosins (Ps) and seco-pseudopterosins (sPs).

In the second report on pseudopterosin derivatives (PsE-PsL),⁴ two compounds (PsE-PsF) displayed the same PsA aglycone (PsAa) part, but with 4-O (instead of 5-O) glycosides, one four-member set (PsG-PsJ) with different aglycones and two (PsK-PsL) with enantiomeric PsAa. However, the aglycone structure of PsG was revised as the 13-epimer of PsAa.⁵

Later on, PsM-PsO and sPsE-sPsG were reported,^6,7 but the structure drawings of the first group displayed xyloside sugar moieties (with revised drawings in Marine Natural Products annual review)⁸, while the text suggested D-arabinose (revised in MNP annual review).⁹

Duplication in structures and names (PsP-PsQ,¹⁰ PsP-PsV,^11,12 PsP-PsZ¹³) resulted, unfortunately, from three almost simultaneous publications in 2004 (the case being revised in MNP annual reviews.^9,14 Many of the trivial names were clarified in the 2007 review¹⁴ [according to communication with the authors]

Finally, the hemisynthetic iso-PsE¹⁵ and a reduced seco-pseudopterosins group (sPsH-sPsI,¹³ sPsJ^16,17 and sPsK¹⁷) were added to the list. The diterpenes from gorgonian octocorals (including an array of nonglycosylated: diterpenes amphilectanes, serrulatanes, elisabethanes, elisapteranes, colombianes, cumbianes, seco-cumbianes, elisabanes, sandresanes, caribanes and related skeletal systems) were reviewed.¹⁸ Occasionally, complementary spectroscopic data were provided^21,22 of known (newly isolated) metabolites for activity testing.^23,24

In Figure 1, a phytane numbering system is used (owing to the direct structural relationship of the structures with the biosynthetic precursor GGPP)^25,26 and the preferred sugar drawings (with standard axial and equatorial substituent orientations)²⁷ and numbering of R subscripts (the same number of ring attachment, thus, R₁ = aglycone) for unequivocal assignments are shown in Figure 2.

Figure 2.

Preferred sugar drawings and numbering.

Along with the absolute configuration of sugars determination, controversial data, revised names, and convenient revisions of NMR data in compilation tables will be discussed next.

Actually, while this manuscript was in preparation, a partial phytane numbering was specified for some structures, including one reported as “iso-PsA” prepared from the dimethoxy PsA-PsF aglycone.²⁸

The Phytane Naming and Numbering System: Introductory Notes and Benefits

In this review, the parent phytane numbering system, already reported for the monocyclic “prenylbisabolanes”²⁵, will be applied in the further cyclised compounds discussed, considered a more convenient atom numbering and naming for “regular” skeletons, such as Ps and sPs. The recommended numbering of side-chains for prenols²⁶ is a convenient addition for a straightforward locant assignment of methyl groups as 3¹, 7¹, 11¹, 15¹, 16 (avoiding the inconsistent exchange of positions 16/17 or 19/20).

The locant direct relationships of the parent skeletons are considered the most remarkable of benefits: position of O-derivatives are always C-4 and C-5 (only OH and OR positions are exchanged). Thus, names for PsC and sPsC as examples are:

3 PsC: (7S,10R,11S,13R)-1,6;1,10;2,13-tricyclophytane-1,3,5,14-tetraen-4-hydroxy-5-yl

3-O-acetyl-α-D-xyloside

s3 sPsC: (7S*,10R*,11S*)-1,6;1,10-bicyclophyta-13,5-trien-4-hydroxy-5-yl

3-O-acetyl-α-arabinoside

Other compounds may be named simply by changing to the new stereochemistry, glycoside name and position, if different (-5-hydroxy-4-yl).

The Identification and Chirality of the Sugar Components

The reported Ps and sPs glycosides are β-D-xylo, α-L-fuco, β-D-arabino and β-L-xylopyranosides. The anomers are designated α or β, depending on the configurational relationship between the anomeric center and the anomeric reference atom. In L-fucopyranoses,²⁹ the 1,5- substituents are on opposite sides (¹C₄ conformation), the axial anomer is α. Vicinal proton-proton coupling constants for pyranose rings were predicted by a simple additivity rule.³⁰

The 1,4- in β-xylosides are trans-diequatorial,^1,2 and the absolute configuration of xylose in PsA-PsD was established by acidic hydrolysis of PsA and treatment in the same manner as D- and L-xylose. D-xylose afforded an [α]²⁰_D + 23° (c 1.64, H₂O), L-xylose [α]²⁰_D = −26° (c 1.54, H₂O) and the sugar component from PsA [α]²⁰_D = + 29° (c 0.95, H₂O). On the other hand, the later reported β-L-xylosides 28-29 (PsP-PsQ^8,9,14, renamed PsX-PsY) had negative optical rotation values ([α]²⁰_D = −24 and −28, respectively, which were nearly identical to that of commercially available L-xylose, treated similarly [-27].

Rotations obtained from pure D-arabinose and PsF were negative {[α]_D −104° (c = 3.0, H₂O) and [α]_D −17.5° (c = 1.7, H₂O) respectively}, pointing out a very strong decomposition (less reliable method) and the axial anomer was β. Although a similar decomposition result was reported in PsG and PsK, L-fucose was assigned on the basis of the negative rotations observed, in spite of the low values: PsG {[α]_D = −20.5° (c = 0.7, H₂O)} and PsK {[α]_D −11.5° (c = 1.0, H₂O)}, whereas from pure L-fucose the result was {[α]_D −75° (c = 10, H₂O), and the axial anomer was α

Attempts to determine the absolute stereochemistry of arabinose in sPsA-sPsD³ failed, “presumably due to decomposition of the sugar under conditions required for glycoside cleavage” (but the L structure was shown). Unfortunately, the same result was reported for sPsH-sPsI (the L structure was also shown). However, the hydrolysates of PsU and PsZ under standard conditions afforded strong negative optical rotations (pointing out D-arabinose resistance in pseudopterosins).¹³ In sPsK,¹⁷ chirality as α-L-fucopyranoside was assumed (signals essentially identical to PsP, unambiguously established previously).

The sugar chirality of aldose enantiomers was established also by a GLC protocol.³¹ Retention times reported when applied to fucose, arabinose and xylose,¹² were:

D/L-fucose derivatives rt: Found 13.4 and 15.2 min; the sample from PsP 15.2 min.

D/L-arabinose derivatives rt: Found 11.5 and 10.4 min; the sample from PsT 11.5 min

D/L-xylose derivatives rt was also reported: 11.05/12.01 min.

Controversial Data Reported of PsM-PsO and SPsE-SPsG Structures

In spite of the poor elucidation data (lacking important coupling constants to assess sugar structure) reported for PsM-PsO and sPsE-sPsG and “non-standard” structures drawing, the paper went through the reviewing process (quite a surprise!). Fortunately, the MNP annual reviews pointed out some inconsistencies (as already mentioned). A diaxial relationship according the J_1,2 = 9.0 Hz of H-C1′,H-C2′ may fit either β-ara or β-xyl glycosides.³⁰ Furthermore, the pseudopterosins were elucidated as D-arabinopyranosides (13-15) with the suggested α-orientation of the 2-methyl-1-propenyl side chain (H-C14, δ 4.96) by “comparison of NMR chemical shifts” with literature values^1,2,4,5 (however, the unacetylated PsF was the only precedent to support that statement), and the negative optical rotation of the solution generated by hydrolysis of 3, which was identical to that of a standard sample of D-arabinose treated similarly (no data). In the corresponding patent, ⁷ ^(p.7) the sugar drawings of PsA (1) and PsM (13) are identical (possible drawing error). Since the real positional isomer of 1 has been synthetised (30, iso-PsA), either 13 is the H-C13 epimer of 30 or the anomeric epimer of PsF (6). Apparently in SciFinder¹² they are listed as acetyl-xylosides (of “1R*, 3S*, 4R*, 7S*-aglycone”), but such a straightforward conclusion (arabinoside or xyloside) is not possible without J_3,4 (for β-xyl: 9.3; for α-ara 3.1 Hz) and apparently the structures remain to be determined³² (data of PsM-PsO, as prospective xylosides or arabinosides, are included in tables of both sugars, for direct chemical shifts comparison of the glycoside part).

Again, in sPsE a “non-standard” sugar drawing was depicted (only one out of five substituent bond orientations was acceptable) and ¹H and ¹³C NMR data assigned to the aglycone components of sPsE-sPsG (no correspondence with those values reported for sPsA aglycone portion nor the sPsH and sPsI glycosides). The large (8.9 Hz) diaxial J_1,2 coupling indicated the equatorial (β) linkage with the aglycone (instead of α), while the L configuration of the fucose was assigned on the basis of a strong negative optical rotation of the sugar obtained by hydrolysis.

The Revised Names Agreement

Introduction

Up to three structures were given the same trivial name (PsP, PsQ), while two different names were given to some compounds.¹⁰ The revision of some trivial names without a joint communication of the authors may be found since 2008³² (revised names are shown in Figure 1) pointing to a proposal by Rodríguez or by Blunt after communication with Rodríguez^14,33

One Structure and two Trivial Names

The identity of L-fucopyranosides PsP (16), PsQ (17) and PsR^8,9,14 (18) and D-arabinosides PsT (20), PsU (21) and PsV (22)^8,9,14 with PsT-PsP-PsQ¹⁰ and PsY-PsU-PsV,¹⁰ respectively, was recognised (in spite of apparent differences in the drawings: PsY/PsU/PsV drawing shows the L-sugar)¹⁰ and the agreed name (with preferred drawing) was as reported by the first group.^8,9,14 The expected ¹C₄ conformation was shown in a structural analysis of methyl α-L-fucopyranoside by x-ray crystallography, NMR spectroscopy, and molecular mechanics calculations”.²⁹ In the supplementary file, a surprise: the structure of PsU¹⁰ is identical to PsU^8,9,14.

Other Renamed Glycosides

Diacetylated glycosides pseudopterosins R, S, W, × and Z (23-27) were pointed out as “unique metabolites to the Old Providence Island collection”.¹⁰ Instead of being renamed as diacetyl derivatives of either PsP (16) or PsT (20) with explicit reference to a double substitution, they were revised as acetyl derivatives of PsQ (17) and PsU (21). On the other hand, PsZ¹⁰ was renamed as PsW (27), but the wrong L-arabinopyranoside sugar, in the main text, was not revised.¹⁴ However, the correct one (with drawing error: 3-O-acetyl missing) is shown in the supplementary information. PsP^6,7 and PsQ^6,7 were renamed as PsX (28) and PsY (29), respectively.

NMR Data Compilation Tables and Structure Elucidation Comments

Introductory Note

The report of leubethanol,³⁴ a serrulatane closely related to erogorgiane, included 1D and 2D NOE experiments and ¹H-NMR full spin analysis. The results may be a useful model for sPs and Ps aglycones. The small calculated J values are a good rationale for broad multiplicities, as well as for prediction of arabinosides or fucosides [equatorial H-C(4′) small axial-equatorial J_3,4 and J_4,5a, and very small eq-eq J_4,5e.³⁰]

Proton Multiplicities

Multiplicities (real) are quoted with the common s (singlet, no J quoted), d (doublet omitted in the tables as implied in every J), t (triplet), q (quartet) or combinations such as dd, td, qd, ddd, tdd, qdd, etc When J values with several nonequivalent systems are very close (or equal), multiplicities may appear as simple “multiplete-like” and are indicated as m* (t* = dd, q* = td/ddd, etc); b is quoted for broad signals (unresolved small couplings) and m to mean “complex or overlapping multiplets” (implied but not quoted if a chemical shift interval is reported).

Data Table Arrangements

Data are presented in separated groups according to multiplicity (m). Groups of m = 0,1, and 2 (aglycone) are in decreasing chemical shifts, while m = 3 and sugar are in locant order. Revised locant assignments show the original position as superscripts. Data of some synthetic compounds are included^5,35,36 (to provide better spectroscopic characterization).

Data of seco-pseudopterosins, aglycones and some methyl ether derivatives are compiled as Table 1 (¹H NMR arranged as reported for sPsK) and Table 2 (¹³C NMR). Tables 1 to 10. ¹H NMR and ¹³C NMR Data of seco-Pseudopterosins and Pseudopterosins.

Table 1.

¹H NMR Data of Seco-Pseudopterosins, Aglycones and Methyl Ether Derivatives.

Compound			s11	s5	s6	s7		s1	s1M	s13	s15		s3	s4	s10	s9	s8	s14
number ^reference			7¹⁷	6^6,7	7⁶	8⁶		1³	8³^c	9³^c	11³^c	21^11,12	3³	4³	8¹⁷	13^11,12	12^11,12	19^11,12
ro	Ph	n,m,^a	F4	2F4	3F4	4F4^b		A5					3A5	4A5	A4	2A4	4A4
1	2	1	6.49 s	6.55	6.54	6.52		6.47 s	6.81 s	6.72 s	6.72	6.72	6.48 s	6.48 s	6.49 s	6.51 b	6.50 b	6.53 s
2	14 bt^a!	1	5.15 7.1 t	5.15	5.14	5.16		5.14/ bt?	5.14 bt?	5.15 bt?	5.15 bt?	5.15 tdd 7.1,1.3,1.2	5.15/ bt?	5.15/ bt?	5.14 7.2 t	-?	5.14 bt?	5.15 tdd 7.1,2.5,1.3
3	7	1	3.14 m	3.33	3.29	3.35		3.10 m	3.02 m?	3.07 m	3.14 m	3.14 m	3.15 m	3.14 m	3.12 m	3.14 m	3.14 m	3.14 m
4	10	1	2.63 m	3.01	2.99	3.02		2.60 m	2.64 s	2.65 b	2.65 m	2.65 m	2.62 m	2.61 m	2.62 m	2.63 m	2.64 m	2.63 m
5	11	1	1.97 m	2.94	2.89	2.93		1.95 m		1.92 2H		2.09-1.77	1.99 m	1.92 m	1.97 m	1.99 m	1.99 m	2.09-1.75
6	13	2	2.07 m 1.95 m	2.10 1.68	2.08 1.65	2.11 1.69						2.09-1.77 (2/5H)			2.06 m 1.95 m	2.04 m 2H	2.05 (2H)	2.09-1.75 (2/5H)
7	8β t^add 8α	2	1.87 12.7,5.9,3.4 1.46 m	1.90 1.40	1.91 1.39	1.89 1.42		1.83 m 1.45 m		1.76 m 1.46 m	--	2.09-1.77 1.50-1.40	--	1.82 m 1.49 m	1.85 12.7,5.9,3.3 1.45 m	1.80 m 1.49-1.16	1.81 m 1.48 m	2.09-1.75 1.50-1.45
8	9α t^add 9β	2	1.79 12.7,6.4,3.3 1.66 m	1.93 1.67	1.90 1.64	1.91 1.65						2.09-1.77	--	1.63 (2H)	1.77 12.7,6.3,3.3 1.66 m		1.66 (2H)	2.09-1.75 1.67 m
9	12	2	1.46 m 1.34 m	1.80 1.19	1.85 1.20	1.83 1.21				1.44 m (2H)		1.50-1.40		1.80 m 1.45 m	1.46 m 1.33 m	1.49-1.16	1.46 (2H)	1.50-1.45
10	3¹	3	2.29	2.21	2.19	2.20		2.23	2.33	2.22	2.22	2.22	2.18	2.14	2.25	2.29	2.27	2.26
11	7¹	3	1.19/6.8	1.17	1.16	1.15		1.16/6.8	1.16/6.9	1.20/6.8	1.16/6.8	1.16/6.9	1.18/6.8	1.19/6.8	1.15/6.9	1.17/6.9	1.17/6.9	1.21/7.0
12	11¹	3	0.71/7.0	0.78	0.77	0.80		0.71/6.9	0.71/6.9	0.71/6.8	0.71/6.8	0.71/6.9	0.73/6.9	0.72/6.9	0.70/6.9	0.71/6.9	0.71/6.9	0.73/7.0
13	15¹	3	1.63	1.67	1.69	1.70		1.61^e	1.62	1.63	1.63	1.63 b	1.61 ^e	1.61 ^e	1.62	1.62 b	1.62	1.63 b
14	16	3	1.71	1.77	1.75	1.79		1.69^e	1.71	1.71	1.72	1.71 b	1.70 ^e	1.70 ^e	1.71	1.71 b	1.71	1.71 b
15	1′	D	5.04/3.8	5.09/8.9	5.10	5.08		5.12/2.7	5.16/3.2				5.18/3.6	5.16/3.4	5.13/3.4	5.15/3.5	5.16/3.4
16	2′	Dd	3.96 3.8,10.0	5.37	4.29	4.35		4.13^d b	4.13/ 3.1,9.5				4.31/ 3.1,9.9	4.09/ 3.5,9.8	4.12/³^′ 3.6,10.0	5.30/ 3.4,9.7	4.10/ 3.5,9.9
17	3′	Dd	4.07/ 10.0,3.2	4.27	5.32	4.26		4.14^d b	4.14 b				5.32/ 3.1,9.9	4.33/ 3.5,9.8	4.17/²^′ 10.0	4.27/ 9.5	4.32/ 9.7 b
18	4′	Dd	3.86/3.2 b	4.10	4.14	5.39		4.07 b	3.87 m?				4.24 b	5.23 b	4.10 b	4.18 b	5.24 bs
19	5′	Qd	4.51/ 6.6 q	4.50	4.49	4.48	5′a dd	4.33/ 12.3 b	4.27/ 12.5 b				4.42/ 12.4 b	4.39/ 13.1,1.0	4.34/ 12.0	4.39/ 12.6,1.6	4.37/ 13.0 b
20	6′	D	1.34/6.6	1.29	1.28	1.30	5′b dd	3.83/ 12.3	3.96/ 14.7,3.2				3.85/ 12.4/2.4	3.89/ 12.1 b	3.84/ 12.0,1.7	3.97/ 12.6,2.5	3.88/ 13.0 b
21	OAc			2.25	2.24	2.26		--					2.27	2.26		2.25	2.17
22	4-OMe							--	3.79	3.78	3.80	3.80					--
23	5-OMe										3.87	3.87						3.78

ro: row order. ph: phytane numbering system (side chains indicated by superscript). n,m,^a: attached proton number, expected, apparent multiplicity. ^b acetylated position/sugar first letter/aglycone position.

italics : not assigned locants in the reference (correlation with parent assignment). d,e: assignments may be reversed (same letter within a column). bt? multiplicity without J?.

substituent orientation (7,10,11): α,α,α. xylosides or arabinosides?8² 4.73/10.8, 2.73 m? unassigned signals; 6 in Experimental error . OH signals not included (D₂O exchg.).

Table 2.

¹³C NMR Data of Seco-Pseudopterosins and Aglycone Methyl Ether Derivatives.

Compound			s1	s10	s9	s8	s3	s4	s11	s5	s6	s7		s14	s15
number ^reference			1³	8¹⁷^/¹⁵	13^11,12	12^11,12	3³	4³	7¹⁷	6⁶	7⁶	8⁶		19^11,12	21^11,12^b
ro	ph	n	A5	A4	2A4	4A4^a	3A5	4A5	F4	2F4	3F4	4F4		A4A	A4A
1	5	0	146.5⁴	146.5/.54	146.0	146.5	146.4⁴	146.7⁴	146.6	144.9	144.8	145.0		142.6	148.8
2	4	0	142.1 ^e1	141.9/.84	141.6	141.9	141.7 ^e1	142.0 ^e1	142.1	140.1	139.9	140.1		145.8	150.4
3	1	0	137.0 ^e5	137.1/.04	137.1	137.1	137.0 ^e5	137.1 ^e5	136.7	138.9	139.0	140.4		136.2	135.6
4	15	0	131.1	131.2/.21	131.2	131.2	131.1	131.1	131.1	132.7	132.8	132.6		131.5	134.9
5	6	0	129.2	129.2/.15	128.9	129.2	129.1	129.3	128.9	132.1	132.0	131.9		127.9	131.2
6	3	0	127.8	127.9/.81	127.3	127.9	127.7	127.7	127.8	128.0	129.9	128.1		126.5	128.6
7	2	0	121.2	121.2/.09	121.6	121.2	121.0	121.1	120.8	123.0	123.4	123.1		121.7	128.4
8	14	1	125.0	124.9/.88	124.8	124.9	124.8	125.0	124.9	124.9	125.1	125.0		124.9	124.9
9	10	1	39.8	39.6/.48	39.5	39.5	39.5	39.9	39.5	39.7	39.8	40.0		39.7	39.3
10	11	1	38.5	38.6/.57	38.4	38.5	38.5	38.4	38.5	40.1	39.6	40.0		38.5	38.8
11	7	1	27.2	27.1/.04	27.7	27.0	27.0	27.2	27.0	26.8	27.0	27.1		27.1	27.2
12	12	2	35.8	35.7/.68	35.7	35.7	35.7	35.8	35.6	35.9	35.7	36.0		35.6	35.7
13	8	2	28.1	27.9/.83	28.0	27.8	27.9	28.1	27.9	27.7	28.0	28.4		27.9	28.0
14	13	2	26.3	26.3/.25	26.2	26.2	26.2	26.4	26.2	27.1	26.9	27.0		26.2	26.3
15	9	2	18.7	18.5/.43	18.5	18.4	18.5	18.9	18.5	19.6	19.2	18.9		18.6	18.3
16	3¹	3	16.4	16.4/.43	16.4	16.4	16.4	16.4	16.4¹⁸	16.1¹⁸	16.4¹⁸	16.2¹⁸		15.9
17	7¹	3	21.1	21.0/20.93	21.0	20.9	21.1	21.1	20.8	21.9¹⁹	21.8¹⁹	22.0¹⁹		20.9
18	11¹	3	17.1	17.2¹⁹/.24	17.2¹⁹	17.2¹⁹	17.3	17.1	16.9¹⁹	16.8²⁰	16.9²⁰	17.0²⁰		16.4	16.4
19	15¹	3	17.7	17.7/.73	17.7	17.7	17.7	17.7	17.6	17.8	18.0	17.9		17.7	17.7
20	16	3	25.6	25.7/.77	25.8	25.7	25.7	25.7	25.6	25.4	25.11	25.0		25.8	25.8
21	1′	1	104.1	103.7/.35	101.5	103.5	103.5	103.4	103.9	103.8	104.0	104.5
22	2′	1	69.7^f	69.7/70.02	71.7	69.6	67.6	70.0	69.0	72.2	68.9	67.8
23	3′	1	69.8^f	69.8/.61	68.1	68.2	73.1	68.4	70.2	67.9	71.9	67.5
24	4′	1	69.3^f	69.3/.12	68.9	71.5	67.6	71.6	67.2	70.0	67.8	71.9
25	5′	1	63.9	63.8/.68	63.5	61.8	63.5	61.9	71.9	67.2	67.0	66.9
26	6′	3							16.1	16.1	15.9	15.8
27	Ac	3			20.9	21.1	20.9	21.0		21.0	20.8	21.3	MeO	60.6	60.4,59.8
28		0			170.9	171.5	171.5	171.2		170.9	170.7	171.0

ro: row order. ph: phytane numbering system (side chains indicated by superscript). n: attached proton number. ^a acetylated position/sugar first letter/aglycone position.

compound number ^reference. e,f: assignments may be reversed (same letter within a column). superscript number: original assignment in exchanged locants.

italics : not assigned locants in the reference (correlation with parent assignment). substituent orientation (7,10,11): α,α,α xylosides or arabinosides.

Table 3.

¹H NMR Data of Pseudopterosin Xylosides.

compound^reference			1 ^1,2	1§	1†	2 ^1,2	3 ^1,2	4 ^1,2	30ξ	28	29	13	14	15
ro	ph	n,m	X5	X5	X5	2 × 5‡	3 × 5	4 × 5	X4	X4	3 × 4	2(X)4	3(X)4	4(X)4
1	14	1	5.10 /8.2	5.12 /9.24	5.11/9.1 5.13/9.2	5.08 /9.0	5.13 /9.2	5.13 /8.5	5.04/ 9.0	5.12 /8.6	5.14 /8.9	4.96 /7.9	4.97	4.96
2	10	1	3.59	3.60	3.63-3.59	3.59	3.80	3.63	2.00/1.94	3.39	3.39	3.39	3.40	3.38
3	13	1	3.56	3.57/8.8 t?	3.63-3.59	3.61	3.65	3.62	3.60-3.52	3.58	3.55	3.55	3.56	3.59
4	7	1	3.53	3.60	3.56/8.9 t?	3.48	3.63	3.61	3.32,3.27	3.58	3.58	3.27	3.29	3.29
5	11	1	1.47	-‡	1.58-1.48	1.61	1.50	1.53	1.54,1.49	3.26	3.26	2.99	3.01	3.03
6	12a	2	c		1.64-1.60^h	c	1.94	2.17 2H	1.68-1.55	1.37	1.36	1.78	1.76	1.77
7	12b		c		2.23-2.17^g	c	2.08		1.68-1.55	1.55	1.53	2.23	2.21	2.20
8	8a	2	c		1.69-1.65^h	1.62	1.65 2H	c	2.17-2.07	1.40	1.40	1.43	1.45	1.42
9	8b		c		2.15-2.10^g	1.73		c	1.48-1.38	1.98	1.98	1.98	1.95	1.96
10	9a	2	c		1.58-1.48^h	c	1.66 2H	1.61 2H	2.17-2.07	1.51	1.51	1.51	1.49	1.53
11	9b		c		1.92-1.85^g	c			1.05-0.98	2.01	2.01	2.10	2.05	2.08
12	3¹	3	1.99	2.05	2.04;2.01	2.04	2.03	2.03	2.09	2.01	2.00	2.09	2.10	2.12
13	7¹	3	1.12/7.4	1.19/6.1	1.18/7.2	1.22/7.2	1.17/7.1	1.17/7.1	1.16/7.0	1.20/6.5	1.20/6.5	1.19/6.5	1.18	1.16
14	11¹	3	1.02/5.7	1.03/7.18	1.03/6.1; = , =	1.04/5.4	1.03/5.9	1.03/6.0	1.02/6.1	1.02/6.9	1.02/6.9	1.00/7.3	1.01	1.03
15	15¹	3	1.64^e	1.67	1.67;1.66	1.67^e	1.68^e	1.67^e	1.66 ^16b	1.66	1.65	1.69¹⁶	1.67¹⁶	1.67¹⁶
16	16	3	1.73^e	1.75	1.75;1.74	1.74^e	1.75^e	1.75^e	1.73 ^16a	1.74¹⁷	1.75¹⁷	1.76	1.78	1.78
17	1′	d	4.49/7.2	4.58/7.69	4.57/7.7;4.53/ =	4.74/7.7	4.59/7.5	4.56/7.6	4.36/7.8	4.97/9.0	4.95/9.4	5.1/9.0	5.09	5.08
18	2′	dd	3.73 m^d	3.72 m	3.82-3.72 3.84-3.70	5.09/ 7.6,9.0	3.87/ 7.5,9.0	3.70/ 7.7,9.2⁴	3.49-3.45	3.83/ 9.7,9.0	3.80/ 9.5,9.4	5.29	4.06	4.06
19	3′	dd	3.76 m^d	3.80 m	3.82-3.72 3.84-3.70	3.59/ 9.0,9.2	4.78/ 9.0,8.9	3.81/ 8.9,9.2	3.37.3.34	3.75/ 10.0,9.7	5.29/ 9.5,9.3	4.07	5.34	4.02
20	4′	m	3.75^d	3.72 m	3.82-3.72 3.84-3.70	3.86	3.91	4.87²	3.60-3.52	4.01/ 10.0,9.5,3.8	4.00/ 9.3,8.9,4.0	3.99	4.00	5.30
21	5′A	dd	3.14/ 10.5,10.2	3.24 10.35,11.64	3.17/10.9,10.9; 3.23/11.5,10.5	3.52/ 11.6,10.5	3.24/ 11.7,10.4	3.20/ 11.4,10.2	3.13/ 11.4 t*	3.87/ bt?	3.89/ bt?	3.83	3.79	3.89
22	5′B	dd	3.95/ 10.4,5.4	4.05 10.35,5.32	3.99/11.5,5.2 4.03/11.4,5.3	4.10/ 11.7,5.3	4.06/ 11.8,5.5	4.09/ 11.6,5.4	3.88/ 11.4,5.4	4.33/ bt?	4.29/ bt?	4.33	4.30	4.36
23	Ac					2.23	2.21	2.10			2.07	2.21	2.19	2.20
24	5-Ac									2.09	2.03

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n,m,*: attached proton number, expected, apparent multiplicity. ‡ acetylated position/sugar first letter/aglycone position.

c: Nonassignable proton resonances. d: No assignment of J values due to peak broadening at room temperature (20 °C).

e-i: assignments may be reversed (same letter within a column). substituent orientation (ph 7,10,11,13): α,α,α,β. xylosides or arabinosides ^4a ?.

§ synthesis of 1²⁷. †synthesis of 1²⁸: NMR concentration dependent (2: 1.8 mg in 0.1 mL; 1: 1.8 mg in 0.4 mL). ξ run in CD₃OD ²² . OH signals not included (D₂O exchg.).

Table 4.

¹³C NMR Data of Pseudopterosin Xylosides.

compound			1	1†	2	3	4	30ξ	28	13	29	14	15
Ro	ph	n	X5	X5	2 × 5‡	3 × 5	4 × 5	X4	X4	2(X)4	3 × 4	3(X)4	4(X)4
1	5	0	144.4	144.9	145.0	144.6	144.7	146.1⁴	145.1⁴	146.1	145.3⁴	146.0	144.9
2	4	0	140.8	140.4	139.2	140.6	140.6	143.3⁵	142.0⁵	144.9	141.8⁵	144.7	144.5
3	2	0	135.4^g	135.9	136.3^g	135.7^g	135.6^g	135.7^2/1	135.0	133.9	134.7	134.1	133.8
4	6	0	133.9^g	134.0	133.9^g	133.9^g	133.9^g	130.7^2/1	129.8¹	129.0	130.2¹	129.2	128.9
5	15	0	129.6^h	129.6	130.1^h	129.9^h	129.9^h	129.9¹⁵	129.7⁶	128.3	129.8⁶	128.0	128.1
6	1	0	128.8^h	128.7	128.4^h	128.8^h	128.7^h	128.2³	127.6¹⁵	126.4	128.2¹⁵	126.7	126.5
7	3	0	121.2	121.5	121.7	121.3	121.3	128.1⁶	121.2	127.3	120.9	127.5	127.1
8	14	1	129.8	130.0	129.3	129.5	129.6	131.6	129.7	129.9	130.0	129.8	130.1
9	10	1	41.7^e	41.1	39.6^e	41.6^e	41.7^e	44.8	42.7	42.9	43.0	43.0	42.8
10	13	1	35.6^e	35.7	35.5^e	35.5^e	35.6^e	36.6	35.6	35.4	35.7	35.2	35.1
11	11	1	30.5	30.9	31.4	30.6	30.6	31.2	30.2	35.3	30.0	34.9	34.9
12	7	1	26.8	26.9	26.2	26.9	26.9	28.5	27.1	26.7	26.8	26.9	26.5
13	12	2	39.4	39.4	39.2	39.4	39.4	40.8	39.4	38.9	39.7	39.0	40.1
14	8	2	29.3^h	29.0	27.9^f	29.2^f	29.3^f	32.0	30.1	30.1	29.9	30.0	29.9
15	9	2	27.5^h	27.2	26.4^f	27.4^f	27.5^f	29.6	28.1	28.1	28.5	28.1	28.0
16	3¹	3	10.9	10.8	10.9	10.8	10.8	12.2	10.8	10.9	11.0	11.1	11.0
17	7¹	3	23.0	22.5	21.6	22.8	22.9	23.5^.7.1	24.0	22.3	24.2	22.5	22.2
18	11¹	3	20.9	21.0	20.9	20.9	20.9	21.4	21.6	19.9	21.4	20.0	20.2
19	15¹	3	17.6	17.7	17.6	17.7	17.7	17.8 ^16a	21.0	16.9	20.9	16.8	17.0
20	16	3	25.6	25.7	25.7	25.7	25.7	25.9 ^16b	25.4	24.9	25.3	25.0	24.7
21	1′	1	106.0	105.9; =	103.9	106.0	105.6	108.3	104.5	105.1	104.6	104.9	105.3
22	2′	1	75.9	76.9;76.8	74.0	72.5ⁱ	-?	75.4	69.6	71.9	70.0	68.9	70.0
23	3′	1	74.0	74.0; =	69.8	79.2	-?	78.0	68.6	67.8	74.1	70.6	69.9
24	4′	1	69.5	69.6; =	75.6	68.8ⁱ	74.3³	71.0	65.9	69.6	67.0	70.3	71.0
25	5′	1	65.9	66.0; =	65.8	65.8	63.1	67.4	67.7	63.2	68.5	62.9	63.6
26	Ac	3			21.0	20.9				20.9	22.3	21.0	21.4
27		0			20.9	171.0	172.4			171.9	175.8	171.5	171.8
28	5-OAc	3							22.5		22.8
29		0							171.3		170.8

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n: attached proton number. ‡ acetylated position/sugar first letter/aglycone position.

substituent orientation (ph 7,10,11,13): α,α,α,β. xylosides or arabinosides?. e-i: assignments may be reversed (same letter within a column).

†synthesis of 1²⁸: NMR (2: 1.8 mg in 0.1 mL; 1: 1.8 mg in 0.4 mL).ξ in CD₃OD.

Table 5.

¹H NMR Data of Pseudopterosin 4-O-Fucosides.

compound^reference			5 ^4,5	5 ³⁵	16 ¹⁰ ^/ ^11,12		19 ⁶ ^/ ²¹	18 ⁶ ^/ ^11,12		17 ⁶ ^/ ^11,12		17 ²¹
ro	ph	n,m,*	F4		F4		2F4‡	3F4		4F4		4F4?!
1	14	1	5.09/8.7	5.1 ov	4.98/9.3 b	4.97/9.1 b	4.93/9.2; =	4.99/9.2	4.98/9.1 b	4.97/9.1;	= /9.2 b	4.99/9.2
2	10	1			2.05 m	2.03 m	ca. 2.05 m; 2.05 m	2.05 m	2.01 m	2.06 m	2.05 m	2.05 m
3	13	1	3.57 m	3.57 m	3.66/8.5*	3.65/ 9.2;8.2	3.66/8.7 q*; =	3.67/8.5 q*	3.66/ 9.1,8.0	3.66/8.6 q*	3.65/ 9.1,8.0	3.66/8.4 q*
4	7	1	3.36 m	3.35 m	3.19/7.0*	3.18 m	3.19 sx*/7.2; =	3.20 sx*/7.0	3.18 m	3.20/sx* 7.2	3.19 qdd 7.6,7.0,6.9	3.20 sx*/7.0
5	11	1			1.22 m	1.20 ov	ca. 1.23 m; 1.23 m	ca. 1.22 m	1.21 m	1.22 m	1.26 m	1.20 m
6	12a	2			1.21 m	1.20	ca. 1.21 m; 1.21 m	ca. 1.22 m	1.18	1.22 m	1.20/10.0	1.20 m
7	12b				1.93 10.5,7.8	1.92 11.3,8.8 b	1.94 m/1.95 m	1.93 m	= / 12.3,7.9,1.9	1.93 m	1.92/ 10.5,7.9	1.93 m
8	8a	2			1.31 m	1.29 m	1.32 m; =	1.32 m	1.29 m	1.32 m	=	1.30 m
9	8b				2.13 m	=	2.15 m; =	2.14 m	2.13 13.1,8.8,4.3	2.14 m	2.15	2.15 m
10	9a	2			0.92/ 12.7,3.2	0.88 m	0.93 q*d/12.7,3.0; =	0.93 q*d/ 12.7,3.2	0.92 m	0.93 q*d/ 12.7,3.0	0.91 m	0.95 q*d/ 12.7,3.2
11	9b				---	2.06 m	--	--	2.05		2.00 m	--
12	3¹	3	2.11 s	2.11 s	2.07 s	2.06 s	2.10 s;2.09 s	2.08 s	2.01 s	2.05 s	2.04 s	2.08 s
13	7¹	3	1.21/7.0	1.23/7.02	1.25/6.8	=	1.25/6.8;1.26/ =	1.26/6.8	1.25/6.7	1.27/6.8	1.26/ =	1.26/6.7
14	11¹	3	1.03/5.9	1.04/6.03	1.02/6.0	1.01/5.8	1.03/5.9; =	1.02/6.0	=	1.02/5.9	=	1.00/6.0
15	15¹	3	1.67 s	1.66 s	1.67 s	= b	1.67 s; =	1.67 bs	=	1.67 s	1.66 b	1.67 s
16	16	3	1.74 s¹⁷	1.74 s	1.71 s¹⁷	1.72 b¹⁷	1.72 s; = ¹⁷	1.72 bs¹⁷	= ¹⁷	1.71 s¹⁷	1.71 b¹⁷	1.72 s¹⁷
17	1′	d	5.00/3.8	5.1/3.9	5.11/3.7	5.11/3.6	5.12/3.7; =	5.18/4.0	5.17/ =	5.14/3.8	5.13/ =	5.16/4.0
18	2′	dd	3.97/ 3.8,8.8³^′	4.02?	4.03/ 3.7,9.5	4.03/ 3.5,9.8	5.24/3.7,10.4; 5.26/ =	4.30/ 4.0,10.4,3.0^a	4.29/ 4.1,10.4	4.04/ 3.8,10.1	4.03/ =	4.27 4.0,10.4,3.0
19	3′	dd	3.82 /2.8²^′	4.12?	4.13/ 9.5 b	4.13/ 9.8 b	4.26/10.4,3.2; =	5.29/ 10.4,3.0	5.28/ 10.5.3.0	4.35/ 10.1,3.3	4.35/ 10.1,3.4	5.30 10.4,3.0;
20	4′	m	4.01 m	3.92?	3.89 ?b	3.90/2.2 b	3.97/3.2 b; 3.95/ =	4.06 b	4.05/2.5	5.21/3.3 b	5.20/2.3	4.06 bs
21	5′	q	4.48 m	4.55/6.33	4.52/6.7	4.51/6.7 b	4.56/6.6; 4.54/ =	4.58/6.6	4.57/6.5	4.55/6.6	4.52/6.5 b	4.59/6.6
22	6′	d	1.31/6.7	1.34/6.53	1.33/6.7	1.32/6.6	1.39/6.6; 1.35/ =	1.33/6.6	1.31/ =	1.17/6.6	1.16/6.5 b	1.33/6.6
23	Ac						2.23;2.21	2.21	=	2.19	=	2.21

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n,m,*: attached proton number, expected, apparent multiplicity. ‡ acetylated position/sugar first letter/aglycone position.

substituent orientation (ph 7,10,11,13): α,α,α,β; α,α,α,α. ‡ 500/600 MHz respectively. a: coupling with the C-2′ hydroxyl group (J = 3.0).

OH signals not included (D₂O exchg.).

Table 6.

¹H NMR Data of Pseudopterosin 5-O-Fucosides.

compound^reference			7 ^4,5	7 ²⁰	11 ^4,5	iE ¹³ †	8 ¹³	9 ^4,5	12 ^4,5	10 ^4,5
ro	ph	n,m,*	F5	F5	F5	F5	2F5‡	3F5	3F5	4F5
1	14	1	4.91/9.0	4.91/9.0	5.08/8.4	5.09/9.2	4.94/9.2	4.95/8.9	5.75/9.0³^′	4.93/9.1
2	10	1	3.67 m	3.66/7.2 q*	3.57 m	3.58/9.2	3.70 m	3.71 m	3.65 m	3.69
3	13	1	3.36 m	3.32/7.8 sx*	3.39 m	3.39 m	3.42 m	3.32 m	3.41 m	3.34
4	7	1		2.05 m		2.05-2.13 (2)
5	11	1		1.22 m		1.05-1.09
6	12a	2		1.21 m
7	12b			1.93 m		1.94-1.99
8	8a	2				1.36-1.43
9	8b					1.50-1.57
10	9a	2				1.59-1.62
11	9b					1.63-1.69
12	3¹	3	1.91 s	1.92	1.94 s	1.96 s	2.02 s	2.01 s	1.99	2.01
13	7¹	3	1.11/6.7	1.12/6.6	1.10/7.0	1.11/7.3	1.19/6.9	1.30/5.0⁶^′	1.19/7.2	1.15/7.6
14	11¹	3	0.96/4.5	0.99/4.8	1.01/5.2	1.02/6.0	1.01/5.5	1.00/4.9	1.03/5.9	1.00/5.1
15	15¹	3	1.61 s	1.61	1.63 s	1.65 s	1.66 s	1.66 s	1.67	1.66
16	16	3	1.67 s¹⁷	1.67¹⁷	1.72 s¹⁷	1.74 s¹⁷	1.72 s¹⁷	1.72 s¹⁷	1.75¹⁷	1.71¹⁷
17	1′	d	5.06	5.05 s	5.03 bs	5.06 s	5.06/3.5	5.17/3.6	5.14/4.0¹⁴	5.09/3.6
18	2′	dd	3.89 b	3.89 b	3.89 bs	3.91 s	5.34/ 3.5,10.4	4.29/ 3.6,10.4	4.30/ 4.0.10.4	4.03/ 3.6,10.1
19	3′	dd	4.10 b	4.11 b	4.11 m	4.15 s*	4.32/ 10.4	5.23/ 10.4,2.5	5.25/ 10.4,2.8¹^′	4.32/ 10.1,2.7
20	4′	m	4.10 m	4.11 b	4.11 m	4.15 s*	3.96 bs	4.06 bs	4.11 bs	5.29/2.7
21	5′	q	4.32 m	4.30/ 6.6 bd?	4.32 m	4.34/ 6.5 q	4.42/ 6.6	4.44/ 6.8	4.45/ 6.6	4.44/ 7.6?
22	6′	d	1.21/6.3	1.21/6.6	1.22/6.3	1.24/6.7	1.38/6.6	1.23/6.8¹⁹	1.29/6.8	1.17/6.6
23	Ac						2.27	2.08	2.06	2.17

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n,m,*: attached proton number, expected, apparent multiplicity. ‡ acetylated position/sugar first letter/aglycone position.

substituent orientation (ph 7,10,11,13): α,α,α,β; α,α,α,α; β,β,β,α. α(5.11)//β(4.97) ^24.

†: no locant assignment. OH signals not included (D₂O exchg.).

Table 7.

¹³C NMR Data of Fucose Glycosides of Pseudopterosins.

			5^4,5	16¹⁰^/^11,12	19¹⁰‡	18¹⁰^/^11,12	17¹⁰^/^11,12	7^4,5	11^4,5	i5¹⁵	8^4,5	9^4,5	12^4,5	10^4,5
ro	Ph	n	F4	F4	2F4	3F4‡	4F4	F5	F5	F5	2F5	3F5	3F5	4F5
1	5	0	144.6	145.2 =	144.5	145.0 =	145.2 =	145.4	145.1	145.4	145.2	145.3	145.2	145.5
2	4	0	1 43.0	143.2/3	143.0	143.1/.0	143.2/.3	142.7	142.2	142.6	142.3	142.5	142.3	142.6
3	2	0	134.0	136.6 =	136.6	136.6 =	136.7 =	135.6	135.1	135.0	136.0	135.7	135.2	135.7
4	6	0	128.9	129.2 =	129.8	129.2/.1	129.3 =	132.5	132.2	133.3	132.4	132.5	132.2	132.5
5	15	0	128.0	128.1/.2	128.4	128.2 =	128.2 =	130.6	130.0	129.9	131.0	130.4	130.1	130.5
6	1	0	126.6	127.8/.7	127.3	127.6/.7	127.8/.7	128.4	128.8	128.9	128.5	128.4	128.6	128.4
7	3	0	126.9	126.8/9	126.7	127.0/126.9	126.9/127.0	121.8	121.2	121.3	121.5	121.9	121.4	121.9
8	14	1	130.2	131.3/4	131.2	131.4 =	131.4 =	131.2	129.6	130.0	131.2	131.2	129.6	131.3
9	10	1	42.8	44.6 =	44.7	44.6 =	44.7/6	44.1	42.8	43.0	43.9	44.1	43.8	44.0
10	13	1	35.1	37.3 =	37.3	37.3 =	37.3 =	37.1	35.7	35.7	37.0	37.1	35.8	37.1
11	11	1	29.6	33.9 =	33.9	33.9 =	33.9 =	34.2⁷	30.2	30.2	34.3	34.2	30.3	34.2
12	7	1	26.8	28.4/5	28.6	28.5/.4	28.4 =	28.2³	28.1	28.3^5?	28.4	28.6	28.1	28.5
13	12	2	39.1	40.2 =	40.1	40.2 =	40.2/1	40.1	39.5	39.6	40.1	40.1	39.6	40.1
14	8	2	30.3	31.7/8	31.9	31.8 =	31.8 =	31.8	30.2	30.5	31.7	31.9	30.3	31.8
15	9	2	27.8	27.8 =	27.8	27.8 =	27.8 =	27.8	27.2	27.3^7?	27.8	27.8	27.3	27.8
16	3¹	3	11.1	13.5 =	13.7	13.6	13.6	12.1	10.8	11.0	11.9	12.0	10.8	12.1
17	7¹	3	22.1	23.3/2	23.1	23.3 =	23.3 =	24.5	23.8	24.3	24.4	24.5	23.8	24.4
18	11¹	3	20.3	20.1 =	20.0	20.1 =	20.1 =	19.9	20.9	21.2	19.9	19.9	20.9	19.9
19	15¹	3	16.8	17.5 =	17.5	17.5 =	17.5 =	17.5	17.6	17.8¹⁶	17.5	17.5	17.6	17.5
20	16	3	24.8	25.4 =	25.4	25.4 =	25.4 =	25.4	25.6	25.9¹⁷	25.4	25.4	25.6	25.3
21	1′	1	103.9	103.0 =	101.3	102.8 =	103.0 =	103.5	103.4	103.7	101.9	103.1	102.9	103.5
22	2′	1	68.5	70.4;69.8	72.3	70.4;67.6	69.5 =	69.4	69.4	69.1	71.7	70.4	67.6	69.5
23	3′	1	69.7	69.6;70.5	68.8	74.3 =	69.1 =	70.6	70.6	70.7	69.1	74.2	74.3	69.0
24	4′	1	71.7	72.2 =	71.4	67.7;70.4	73.6 =	72.3	72.4	72.4	72.6	67.4	70.5	73.8
25	5′	1	67.3	67.3 =	67.4	67.1	66.3;66.4	67.6	67.6	67.8	67.8	67.3	67.3	66.6
26	6′	3	15.5	16.2 =	16.1	16.1	16.3 =	16.3	16.2	16.4	16.2	16.2	16.5	16.3
27	Ac	3			21.0	20.8;21.1	20.8 =				20.1	20.9	20.9	20.7
28		0			170.9	171.7 =	171.9 =				170.9	171.6	171.5	171.9

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n: attached proton number. ‡ acetylated position/sugar first letter/aglycone position.

substituent orientation (ph 7,10,11,13): α,α,α,β; α,α,α,α; β,β,β,α.. E,F,G run in a CDCl₃/CD₃OD mixture.

Table 8.

¹H NMR Data of Pseudopterosins Arabinose Glycosides.

compound^reference			6 ^4,5	20 ¹⁰ ^// ²¹		20 ^11,12	13 ⁶	22 ¹⁰	22 ^11,12	14	15	21 ¹⁰	21 ^11,12
ro	Ph	n,m,*	A4	A4			2A4	3A4‡		3A4	4A4	4A4
1	14	1	5.09 /9.0	4.93 /9.3 b	4.94 /9.1 b	4.95 /9.0 b	4.96/7.9	4.98/ 11.5 b	4.97 /9.1 b	4.97	4.96	4.96 /9.1	4.95 /9.2 b
2	10	1	3.58 /7.7 b	3.62 /8.7 q*	3.61 /8.7 q*	3.65 /9.0,8.2	3.55	3.67 /8.7 q?	3.66 /9.3,8.3	3.56	3.59	3.67	3.65 /9.4,8.5
3	13	1	3.33	3.12/7.2	3.12/7.2	3.17 m	3.27	3.20/7.2	3.19 m	3.29	3.29	3.19	3.18 m
4	7	1		ca. 2.02	2.02	2.03 m	3.39	2.05	2.01 m	3.40	3.38	2.05	2.00 m
5	11	1		ca. 1.23	1.22	1.20 m	2.99	1.20	1.21 m	3.01	3.03	1.22	1.20 m
6	12a	2		ca. 1.22	1.22	1.23 m	1.78	1.22	1.18 m	1.76	1.77	1.23	1.20 m
7	12b			1.90/ 10.2,6.3	1.90/ 10.1,6.3	1.92/ 10.6,8.0	2.23	1.93	1.93/ 12.3,7.9,1.9	2.21	2.20	2.25	1.92/ 10.7,8.0 b
8	8a	2		1.30	1.30	1.30 m	1.43	1.33	1.29 m	1.45	1.42	1.31	1.30/ 13.3,8.5,4.2
9	8b			2.08	2.08	2.15 m	1.98	2.15	2.15 m	1.95	1.96	2.13	2.14 m
10	9a	2		0.88/ 12.7,3.2	0.88/ 12.6,3.2	0.87 m	1.51	0.93 12.7,3.3	0.92 m	1.49	1.53	0.92/ 12.7,3.2	0.90 14.0,7.0,4.5
11	9b			-	-	2.05 m	2.10	2.05	2.05 m	2.05	2.08	2.02	2.03 m
12	3¹	3	2.12	1.97	=	2.07	2.09	2.07	2.08	2.10	2.12	2.06	2.05
13	7¹	3	1.21/6.9	1.18/6.6	1.18/6.6	1.25/6.7	1.19/6.5	1.26/8.5	1.26/6.8	1.18	1.16	1.27/1.8	1.26/6.7
14	11¹	3	1.03/5.7	1.00/5.6	1.04/5.6	1.01/5.9	1.00/7.3	1.02/7.5	1.02/5.9	1.01	1.03	1.02/5.9	1.02/6.0
15	15¹	3	1.73	1.68	=			1.71 b	1.72 b	1.78	1.78	1.72 b	1.71 b
16	16	3	1.66	1.64	=	1.66 b	1.69	1.66 b	1.67 b	1.67	1.67	1.66 b	1.66 b
17	1′	d	5.06/1.0	5.10/2.5	=	5.15/3.2	5.10/9.0	5.22/3.6	5.21/3.8	5.09	5.08	5.18/3.6	5.17/3.6
18	2′	dd	4.03/m	4.17 7.3 b	=	4.15 m	5.29	4.33/ 3.8,10.0	4.32/ =	4.06	4.06	4.11 3.5,9.8	4.10 3.6,9.9
19	3′	dd	4.03/m	4.12 /7.3 b	4.13 /7.2 b	4.13 m	4.07	5.31 10.0,3.8	= / 10.0,3.1	5.34	4.02	4.32 9.9,3.4	4.33 9.9,3.5
20	4′	m	4.03	4.08/b	=	4.11 m	3.99	4.27	4.26/1.4	4.00	5.30	5.24	5.23 bs
21	5′A	d(d)	3.82/ 12.4,1.8	3.78 12.6	=	3.87 12.0 b	3.83	3.86 16.0,1.5	= 12.6,2.5	3.79	3.89	3.89 13.0,1.9	3.88/ 13.2 b
22	5′B	d(d)	4.35 11.9	4.25 12.6	=	4.35 12.6	4.33	4.42 11.7	4.40/ =	4.30	4.36	4.36 13.0 b	4.36; 13.2 b
23	Ac	s					2.21	2.22	2.21	2.19	2.20	2.16	2.16

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n,m,*: attached proton number, expected, apparent multiplicity. ‡ acetylated position/sugar first letter/aglycone position.

substituent orientation (ph 7,10,11,13): α,α,α,β;. αααα; βββα. g unassigned data. OH signals not included (D₂O exchg.).

Table 9.

¹³C NMR Data of Arabinose Glycosides of Pseudopterosins.

			6	20¹⁰^/^11,12	13	22¹⁰^/^11,12	14	15	21¹⁰^/^11,12
ro	ph	n	A4	A4	2A4	3A4‡	3A4	4A4	4A4
1	5	0	144.6	145.0/2	146.1¹⁰	145.0 =	146.0¹⁰	144.9¹⁰	145.2 =
2	4	0	142.1	143.1 =	144.9	142.9 =	144.7	144.5	143.1 =
3	2	0	134.2	136.6/.7	133.9	136.7 =	134.1	133.8	136.8 =
4	6	0	129.0	129.3/.2	129.0	129.2 =	129.2	128.9	129.2/.3
5	15	0	128.2	128.1/.2	128.3	128.2 =	128.0	128.1	128.2 =
6	1	0	126.7	127.9/.8	126.4	127.6 =	126.7	126.5	127.8 =
7	3	0	127.1	126.8/127.1	127.3	127.1 =	127.5	127.1	126.9/127.0
8	14	1	130.2	131.3 =	129.9	131.4 =	129.8	130.1	131.3 =
9	10	1	44.7	44.6/.7	42.9	44.7 =	43.0	42.8	44.7 =
10	13	1	37.3	37.3 =	35.4	37.3 =	35.2	35.1	37.3 =
11	11	1	33.9	33.9 =	35.3	33.9 =	34.9	34.9	33.9 =
12	7	1	28.5	28.4/.5	26.7	28.5 =	26.9	26.5	28.5 =
13	12	2	40.2	40.2 =	38.9	40.2 =	39.0	40.1	40.2 =
14	8	2	31.8	31.7/.8	30.1	31.8 =	30.0	29.9	31.8 =
15	9	2	27.8	27.8 =	27.6	27.8 =	28.1	28.0	27.8 =
16	3¹	3	11.5	13.8/.9	10.9	13.8 =	11.1	11.0	13.9 =
17	7¹	3	22.2	23.3 =	22.3	23.2 =	22.5	22.2	23.2/.4
18	11¹	3	20.4	20.0/.1	19.9	20.1 =	20.0	20.2	20.1 =
19	15¹	3	16.9	17.5 =	16.9	17.5 =	16.8	17.0	17.5 =
20	16	3	24.9	25.4/.5	24.9	25.5 =	25.0	24.7	25.4 =
21	1′	1	104.1	103.8/.3	105.1	103.1/ =	104.9	105.3	103.1/ =
22	2′	1	68.9	69.5^a/.9	71.9	68.1/.0	68.9	70.0	70.0/ =
23	3′	1	68.9	69.5^a/.1	67.8	73.3/ =	70.6	69.9	68.2/ =
24	4′	1	68.7	69.4^a/.6	69.6	67.5/ =	70.3	71.0	71.5/ =
25	5′	2	63.8	64.0/63.9	63.2	63.7/ =	62.9	63.6	61.9/ =
26	Ac	3			20.9	21.1/ =	21.0	21.4	21.1/ =
27		0			171.9	171.6/ =	171.5	171.8	171.3/ =

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n: attached proton number.‡ acetylated position/sugar first letter/aglycone position.

same signals within a column may be reversed.

substituent orientation (ph 7,10,11,13):α,α,α,β; αααα; xylosides or arabinosides.

Table 10.

¹H NMR and ¹³C NMR Data of Pseudopterosin Dicetylated Glycosides (Revised Names)^7.

compound			26	25	27	24	23				26	25	27	24	23
ro	ph	n,m,*	24A4‡	34A4	34A4	24F4	34F4		ph	n	24A4	34A4	34A4	24F4	34F4
1	14	1	4.91/9.3	4.96/9.2	5.10/9.1 b	4.92/9.4 b	4.97/9.2	1	5	0	144.6	144.0	144.6	144.5	145.0
2	10	1	3.65 9.0/8.4	3.66 9.3/8.4	3.58 bm	3.65 9.0/7.9	3.67 9.0/7.9	2	4	0	142.9	143.0	142.6	143.0	143.1
2	10	1	3.65 9.0/8.4	3.66 9.3/8.4	3.58 bm	3.65 9.0/7.9	3.67 9.0/7.9	3	2	0	136.8	136.7	135.1	136.7	136.6
3	13	1	3.18 m	3.18 m	3.35 m	3.18 m	3.19 m	4	6	0	129.9	129.3	129.6	129.4	129.3
4	7	1	2.05 m	2.05 m	2.04 m	2.03 m	2.04 m	5	15	0	128.4	128.2	128.8	128.4	128.2
5	11	1	1.22 m	1.24 m	1.62 m	1.23 m	1.23 m	6	1	0	127.3	127.8	127.1	127.2	127.6
								7	3	0	126.7	127.0	127.8	126.6	127.0
6	12a		1.21 m	1.18 m	1.65 m	1.20 m	1.22 m	8	14	1	131.1	131.3	130.2	131.1	131.4
7	12b		1.94 m	1.93 10.8,8.0	---	1.92 m	1.93 10.5,7.8	9	10	1	44.7	44.6	43.2	44.7	44.6
7	12b		1.94 m	1.93 10.8,8.0	---	1.92 m	1.93 10.5,7.8	10	13	1	37.3	37.3	37.5	37.3	37.3
8	8a		1.32 m	1.30 m	1.46 m	1.30 m	1.33 m	11	11	1	33.9	33.9	29.9	33.8	33.9
9	8b		2.16 m	2.07 m	2.10 m	2.15 m	2.13 m	12	7	1	28.6	28.4	27.3	28.6	28.4
10	9a		0.89 m	0.92 m	1.12 m	0.89 m	0.92 m	13	12	2	40.1	40.1	39.4	40.1	40.2
11	9b		2.07 m	2.01 m	2.12 m	2.04 m	2.02 m	14	8	2	31.9	31.7	30.7	31.9	31.8
								15	9	2	27.8	27.8	28.2	27.8	27.8
12	3¹	3	1.65/1.0	1.66 b	1.66 b	1.66 b	1.67 b	16	3¹	3	13.9	13.9	12.1	13.8	13.6
13	7¹	3	2.08	2.07 m	2.01	2.08	2.07	17	7¹	3	23.1	23.3	22.9	23.1	23.2
14	11¹	3	1.24/6.7	1.26/6.8	1.23/7.0	1.23/6.0	1.19/6.6	18	11¹	3	20.0	20.0	21.1	20.0	20.1
15	15¹	3	1.02/6.0	1.02/6.0	1.03/6.0	1.02/5.8	1.02/6.1	19	15¹	3	17.5	17.5	17.6	17.5	17.5
16	16	3	1.71/0.9	1.71 b	1.7 b	1.71 b	1.72 b	20	16	3	25.4	25.4	25.7	25.4	25.4
17	1′		5.15/3.4	5.23/3.7	5.24/3.6	5.14/3.6	5.20/3.9	21	1′	1	101.5	103.1	102.9	101.4	102.8
18	2′		5.32 3.4,10.0	4.30/ 3.8,10.3	4.31/ 3.7,10.1	5.26 3.7,10.6	4.25 3.8,10.2	22	2′	1	71.2	67.7	68.0	71.1	70.4
19	3′		4.38 10.2,3.5	5.39/ 10.3,3.2	5.39/ 10.1,3.3	4.45 10.7,3.5	5.38 10.2,3.2	23	3′	1	66.6	70.3	70.4	67.2	74.3
20	4′		5.27/b	5.44/1.1b	5.44/b	5.38/2.4b	5.40/3.1	24	4′	1	71.6	68.8	68.7	73.6	67.7
21	5′A		4.36/ 14.3,1.5	4.45/ 12.9	4.47/ 13.1	4.62/ 6.4	4.66/ 6.7	25	5′	1	61.7	61.9	62.0	66.7	67.1
22	5′B		3.98 13.0,2.6	3.85 13.0,2.0	3.85 13.1,2.0	1.25/6.0	1.26/6.8	26	6′	3				16.3	16.1
23	Ac		2.19	2.14	2.14	2.23	2.17	27	Ac	3	20.9	20.9	20.9	21.0	20.8
								28		0	170.5	171.0	170.2	170.6	170.5
24	Ac		2.24	2.10	2.11	2.23	2.09	29	Ac	3	21.0	20.8	20.9	20.8	20.6
								30		0	170.7	170.3	171.0	171.2	170.9

ro: row order. ph: phytane numbering system (side chains indicated by superscript).

n: attached proton number. m,*: expected, apparent multiplicity. ‡ acetylated position/sugar first letter/aglycone position.

substituent orientation (ph: 7,10,11,13): αααα; αααβ.

Revised Assignments According to the Logical Sequence of Coupling Constants

Before 2D-COSY spectra were developed, the proton-proton vicinal relationship was established through the logical sequence of coupling constants. Signal reassignments have been proposed for sPsJ 4-(β-D-arabinopyranoside), PsD [5-(4-O-acetyl-β-D-xylopyranoside)], PsE 4-(α-L-fucopyranoside) and PsL [5-(3-O-acetyl-α-L-fucopyranoside)], and are summarized in Table 11.

Table 11.

Revised Assignments According to the Logical Sequence of Coupling Constants.

	s10 Table 1	4 Table 3		5 Table 5	12 Table 6
	4-(β-D-ara)	[5-(4-O-acetyl-β-D-xyl)]		4-(α-L-fuc)	[5-(3-O-acetyl-a-L-fuc)]
			14		5.75/9.0³^′
1′	5.13/3.4	4.56/7.6	1′	5.00/3.8	5.14/4.0¹⁴
2′	4.12/3.6,10.0³^′	3.70/7.7,9.2⁴^′	2′	3.97/3.8,8.8³^′	4.30/4.0.10.4
3′	4.17/10.0²^′	3.81/8.9,9.2	3′	3.82/2.8²^′	5.25/10.4,2.8¹^′
4′	4.10 b	4.87²^′	4′	4.01 m	4.11 bs
5′	4.34/12.0	3.20/11.4,10.2	5′	4.48 m	4.45/6.6
5′	3.84/12.0,1.7	4.09/11.6,5.4	6′	1.31/6.7	1.29/6.8
OAc		2.10	OAc		2.06

Sugar Acetylation Effects

Downfield chemical shifts were recognised as showing the location of sugar acetylation. A related effect in the vicinal ¹³C chemical shifts has been observed. The chemical shift effects on 2′-O-acetylation [2′-OAc] ― [2′-OH] are displayed in Table 12.

Table 12.

Chemical Shifts Effects in Pseudopterosins and Seco-Pseudopterosins Acetylated Glycosides.

OAc	[OAc] – [OH]		Δδ H-C1′	OAc	Δδ C (OAc-OH)
2 3 4	(PsB - PsA) (PsC - PsA) (PsD - PsA)	(14β,5-xyl)	5.09-3.73 = + 1.36 4.78-3.76 = + 1.02 4.87-3.75 = + 1.12	2→1 2→3 3→2 3→4 4→3 4→5	103.9-106.0 = -2.1 69.8-74.0 = -4.2 72.5ⁱ-75.9 = -3.4 68.8ⁱ-69.5 = -0.7 ? -74.0 = ??? 63.1-65.9 = -2.8
2	[OAc] – [OH]		Δδ H-C2		Δδ C1
PsM (14α) -iPsA -PsE -PsF -PsT PsY→T		(14β,4-xyl) (14β,4-fuc) (14β,4-ara) (14α,4-ara) (14α,4-ara)	5.29-3.47 = + 1.82 5.29-3.97 = + 1.32 5.29-4.03 = + 1.26 5.29-4.17 = + 1.12 5.29-4.15 = + 1.14		105.1-108.3 = -3.2 105.1-103.9 = + 1.2 105.1-104.1 = + 1.0 105.1-103.8 = + 1.3 105.1-103.3 = + 1.8	101.5-108.3 = -6.8 101.5-103.9 = -2.4? 101.5-104.1 = -2.6? 101.5-103.8 = -2.3? 101.5-103.3 = -1.8?
PsH (14α)-PsG -PsK -iPsE		(14α,5-fuc) (14α,5-fuc) (14β,5-fuc)	5.34-3.89 = + 1.45 5.34-3.89 = + 1.45 5.34-3.91 = + 1.43		101.9-103.5 = -1.6 101.9-103.4 = -1.5 101.9-103.7 = -1.8
PsS (14α)-PsP -PsE PsP→S -PsT→P ^a		(14α,4-fuc) (14β,4-fuc) (14α,4-fuc)	5.24-4.03 = + 1.21 5.24-3.97 = + 1.27 5.26-4.03 = + 1.23		101.3-103.0 = -1.7 101.3-103.0 = -1.7 101.4-103.0 = -1.6
PsX → 2PsU -PsT ^a -PsY → T ^a		(14α,4-ara)	5.32-4.17 = + 1.15 5.32-4.15 = + 1.17		101.5-103.8 = -1.8 101.5-103.3 = -1.8
sPsI-sPsJ		(4-ara)	5.30-4.12 = + 1.18		101.5-103.7 = -2.2
sPsE-sPsK ^b		(4-fuc)	5.37-3.96 = + 1.41		103.8-103.9 = -0.1	101.8-103.9 = -2.1?

→ revised as; ^b different anomeric bond.

The controversial data of PsM are out of range. Thus, the chemical shift is either “true” or a simple typing error (101.5 may fit quite well). The extremely large downfield shift for iPsA data may be due (in part) to a solvent effect (MeOH-d4: ca. 4.0 ppm).

There is also a remarkable apparent lack of effect in sPs-4-fucosides (103.8/103.9), but the sPsI/sPsJ 4-arabinoside pair displayed the expected shift (101.5/103.7: Δδ −2.2 ppm). In Ps pairs, only PsM, as mentioned, appears again as a real effect or another simple typing error (101.8 may fit well: Δδ −2.1 ppm).

Small shift differences (ca.< 0.2 ppm) may not be significant as recorded for the anomeric proton (4.74- 4.49 = + 0.25) with 2′-OAc. Overlapping multiplets in PsA (2′, 3′, 4′/14,7) were partially separated in monoacetates. Curiously, a real typing error occurred with the 5′a PsB proton: it appears at ca. 3.25 ppm in the figure, but was printed as 3.52! (Table 3).

The ¹³C Chemical Shifs of 4- or 5-O-Glycosyl sPs Derivatives

As pointed out,¹⁶ the ¹³C data of the aglycone moieties for 4-O-glycosylated seco-pseudopterosins (eg, sPsK and sPsJ)¹⁷ and 5-O-glycosylated congeners (seco-PsA–seco-PsD) are coincidentally closely similar to each other.

Actually, the average shielding effect for sPsA-sPsD observed (C-4 arabinoside sPs) when compared to the hydroxyl substituted C-5, were 141.93 and 146.53 (Δ 4.6) (Table 13), while for sPsH-sPsJ (C-5 arabinoside sPs) they were 146.33 and 141.8 (Δ 4.53). Whereas the C-4 unsubstituted fucoside sPsK (J_1′,2′ 3.8 Hz, axial anomeric bond) data are quite close (146.6 and 142.1), the average reported for sPsE-sPsG (J_1′,2′ 8.9 Hz, equatorial anomeric bond) are 144.90 (-1.7) and 140.03 (-2.1). Thus, the sPsK and arabinoside derivatives data are highly homogeneous, regardless of glycoside position, and the sPsE-sPsG difference may result from a change of anomeric bond configuration (Figure 4).

Figure 3.

Revised possible sugar structures of PsM and sPsE.

Table 13.

¹³C NMR Data of C-OR sPs and Ps Aglycones.

sPs	^a		a	b	a-b	Ps	^a		a	b	a-b	Ps	^a		a	b	a-b
s1	A5	4-OH	1465	1421	4,4	1	X5	4-OH	1449	1404	4,5	11	F5	4-OH	1451	1422	2,9
s3	3A5	4-OH	1464	1417	4,7	1	X5	4-OH	1446	1406	4	12	2F5	4-OH	1452	1423	2,9
s4	4A5	4-OH	1467	142	4,7	1	X5	4-OH	1444	1408	3,6	7	F5	4-OH	1454	1427	2,7
						2	2 × 5	4-OH	145	1392	5,8	8	2F5	4-OH	1452	1423	2,9
s10	A4	5-OH	1465	1419	4,6	3	3 × 5	4-OH	1446	1406	4	9	3F5	4-OH	1453	1425	2,8
s9	2A4	5-OH	146	1416	4,4	4	4 × 5	4-OH	1447	1406	4,1	10	4F5	4-OH	1455	1426	2,9
s8	4A4	5-OH	1465	1419	4,6			4-9avg	1447	140 367	4333			4-9avg	145 283	142 433	2,85
s11	F4	5-OH	1466	1421	4,5	13	2A4	5-OH	1461	1449	1,2
						14	3A4	5-OH	146	1447	1,3	5	F4	5-OH	1446	143	1,6
		avg (4:6)	146 533	141 933	4,6	15	4A4	5-OH	1449	1445	0,4	16	F4	5-OH	1452	1432	2
		avg (8:11)	1464	141 875	4,53			11-13avg	145 667	1447	0967	17	4F4	5-OH	1452	1432	2
		avg (4:11)	146 457	141 900	4,7	6	A4	5-OH	1446	1421	2,5	18	3F4	5-OH	145	1431	1,9
						20	A4	5-OH	145	1431	1,9	19	2F4	5-OH	1445	143	1,5
s5	2F4	5-OH	1449	1401	4,8	21	4A4	5-OH	1452	1431	2,1	23	34F4	5-OH	145	1431	1,9
s6	3F4	5-OH	1448	1399	4,9	22	3A4	5-OH	145	1429	2,1	24	24F4	5-OH	1445	143	1,5
s7	4F4	5-OH	145	1401	4,9	25	34A4	5-OH	145	143	2			12-18avg	144 857	143 086	1771
		17-19avg	144 900	140 033	4738	26	24A4	5-OH	1446	1429	1,7
						27	34A4	5-OH	1446	1426	2
								15-21avg	144,8 571 429	14 281 429	204 286

acetylated position/sugar first letter/aglycone position.

Surprisingly, the averages of Ps 5-O-xylosides are 144.7 and 140.4 (Δ 4.3), of 4-O-arabinosides 144.71 and 142.81 (Δ 1.9) ppm, 4-O-fucosides 144.86 and 143.09 (Δ 1.8), and of 5-O-fucosides 145.28 and 142.43 (diacetylated glycosides included) (Δ 2.85). Thus, large differences in glycosyloxy substitution compared with that of the vicinal free hydroxyl substituted position are observed in sPs aglycone moieties and also for Ps 5-O-xylosides. Other Ps display a smaller range, from 1.6 to 2.8 ppm. The PsM-PsO group averages are 145.7 and 144.7 (Δ = 0.97).

Further Comments on Seco-Pseudopterosins Data

Some multiplicities are not rigorous. H-14 is reported as br t (actually t*), but no J is quoted. Whereas a t* may be due to coupling with the vicinal H₂-13, signal broadening may result from long-range allylic (⁴J) couplings with (one or both) terminal methyl groups. Actually, for the sPsH aglycone 5-methoxy and 4,5-dimethoxy derivatives they have been reported as tdd (7.1, 2.5, 1.3 Hz and 7.1, 1.3, 1.2 Hz).^11,12 A t* (J = 7.1 Hz) is reasonabe, but couplings with terminal methyl groups may be expected as q or qq.

In sPsE-sPsG the separation of geminal protons (Δδ) for H₂-8, H₂-9, H₂-12 and H₂-13 are quite different from those of sPsK and also the methines H-7, H-10 and H-11. These results support a certain difference in the sugar attached, but structural elucidation could not be concluded, as mentioned already.

Assignments of the HC(14) and HC(1′) Methine Doublets

The doublets are reported with close chemical shifts (occasionally overlapping), but are easily distinguished because small HC(1′) equatorial-axial couplings in fucosides (Ps, Table 5; sPs, Tables 1,6) and arabinosides (Ps, Table 8; sPs, Table 1). However, large HC(1′) axial-axial couplings in xylosides (Table 3) are close to 9.0 Hz, as found for HC(14). Exchange of assignments may be carefully excluded.

The Dimethyl Vinyl Unit (HC-14, C-15, H₃C-16 and H₃C-15¹) NMR Data

In the early reports, the assignments of the methyl groups were not disclosed (“may be reversed: same letter within a column”). Assignments in the tables were revised according to the results of the stereochemical analysis of leubethanol,³⁴ showing the H-14 signal enhancement on H₃-16 irradiation (as a figure, although not quantified, as was for β,β-dimethylacrylic acid).³⁷ Thus, locants assignment were fixed in the HMQC: H₃C-15¹ (δ 1.582/17.49) and H₃C-16 (δ 1.683/25.59).

Furthermore, H-14 was reported at δ 4.97 ppm when the 2-methyl-1-propenyl side chain has an α-orientation” (β H-13), while with a β-oriented side chain exhibits a downfield shift to δ 5.11 ppm.⁵

Concentration and Temperature Effects

¹H NMR and ¹³C NMR spectra may vary with concentration and temperature.³⁶ ¹H NMR spectra of the peracetylated derivatives of PsP-S and PsT-V were recorded at different temperatures (20, 40, 60°).¹⁰ When recorded at 20 °C, the spectrum showed two sets (ca. 45:55 ratio) of signals for some peaks, which might correspond to two conformers of the tetraacetate, or broad signals (the interchange of the two conformers at this temperature was not rapid enough for sharp peaks), pointing out a “higher energy barrier for the rotation of the fucose derivative, compared to that of the arabinose derivative” caused by acetylation of the C-5 hydroxyl, as well as the hydroxyl groups of the sugar moiety.

Concluding Remarks

The improved consistency of reported chemical shifts and coupling constants revision (through the proposed reassignments) may provide some answers, but some questions remain to be properly addressed, while pointing out presumed typing errors or misassigned structures. Hopefully, data revised and compiled may be useful for further studies, axial and equatorial bonds will show standard orientations in sugar chair cyclohexane drawings, NMR multiplicity will be treated rigorously, and the phytane naming/numbering proposal may proof useful in structure relationships.

Footnotes

Acknowledgments

The sending of requested copies of papers is gratefully acknowledged to Professors Athar Ata, Yoshinori Fujimoto and Dan Little, and useful answers and comments to Professor Carmenza Duque and Hebelin Correa.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship and/or publication of this article.

Ethical Approval

Not applicable, because this article does not contain any studies with human or animal subjects.

Informed Consent

Not applicable, because this article does not contain any studies with human or animal subjects.

ORCID iD

Josep Coll Toledano

Trial Registration

Not applicable, because this article does not contain any clinical trials.

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Pseudopterosins and Seco -Pseudopterosins: Compilation and Revision of Conflicting NMR Data,Names,Numbering Systems and Structural Elucidation

Abstract

Keywords

The Phytane Naming and Numbering System: Introductory Notes and Benefits

The Identification and Chirality of the Sugar Components

Controversial Data Reported of PsM-PsO and SPsE-SPsG Structures

The Revised Names Agreement

Introduction

One Structure and two Trivial Names

Other Renamed Glycosides

NMR Data Compilation Tables and Structure Elucidation Comments

Introductory Note

Proton Multiplicities

Data Table Arrangements

Revised Assignments According to the Logical Sequence of Coupling Constants

Sugar Acetylation Effects

The 13C Chemical Shifs of 4- or 5-O-Glycosyl sPs Derivatives

Further Comments on Seco-Pseudopterosins Data

Assignments of the HC(14) and HC(1′) Methine Doublets

The Dimethyl Vinyl Unit (HC-14, C-15, H3C-16 and H3C-151) NMR Data

Concentration and Temperature Effects

Concluding Remarks

Footnotes

Acknowledgments

Declaration of Conflicting Interests

Funding

Ethical Approval

Informed Consent

ORCID iD

Trial Registration

References

The ¹³C Chemical Shifs of 4- or 5-O-Glycosyl sPs Derivatives

The Dimethyl Vinyl Unit (HC-14, C-15, H₃C-16 and H₃C-15¹) NMR Data