The reactions of 2′-benzyloxyflavanones 9b,c with thallium(III) nitrate or iodobenzene diacetate in the presence of perchloric or sulfuric acid in trimethyl orthoformate was studied. Depending on the substitution pattern and the conditions, these compounds underwent 2-aryl migration (9b → 11a) and/or ring contraction (9c → 10b + 11b) and dehydrogenation (9c → 12). A probable mechanism of these transformations is discussed.
DewickPM. (1986) in: HarborneJB. (Ed): Flavonoids, Advances in Research Since 1986, pp. 166–180, Chapman and Hall, London, 1994
2.
LaneGA, SutherlandORW, SkippRA. (1987) Isoflavonoids as Insect Feeding Deterrents and Antifungal Components from Roots of Lupinus augustifolius. Journal of Chemical Ecology, 13, 771–783.
3.
KamatVS, ChuoFY, KuboI, NakanashiK. (1981) Antimicrobial Agents from an East African Medicinal Plant Erythrina abyssinica. Heterocycles, 15, 1163–1170.
EnglerTA, LaTessaKO, IynegarR, ChaiW, AgriosK. (1996) Stereoselective Syntheses of Substituted Pterocarpans with Anti-HIV Activity, and 5-Aza-/5-Thia-pterocarpan and 2-Aryl-2,3-dihydrobenzofuran Analogues. Bioorganic & Medicinal Chemistry, 4, 1755–1769.
6.
NakagawaM, NakanishiK, DarkoL.LászlóVJA. (1982) Structures of Cabenegrins A-I and A-II, Potent Anti-Snake Venoms. Tetrahedron Letters, 23, 3855–3858.
7.
DarkoLL, NakanishiK, NakagawaM. (1984) European Patent Appl. D.E.P. 89229 1983. Chemical Abstracts, 100, 39587.
8.
IshiguroM, TatsuokaT, NakatsukaN. (1982) Synthesis of (±)-Cabenegrins A-I and A-II. Tetrahedron Letters, 23, 3859–3862.
9.
TőkésLA, LitkeiG, GulácsiK, AntusS, Baitz-GácsE, SzántayC, DarkoLL. (1999) Absolute Configuration and Total Synthesis of (-)-Cabenegrin A-I. Tetrahedron, 55, 9283–9296.
10.
KissL, KurtánT, AntusS, BényeiA. (2003) Chiroptical Properties and Synthesis of Enantiopure cis and trans Pterocarpan Skeleton. Chirality, 15, 558–563.
11.
CockerW, DahlT, DempseyC, McMurrayTBH. (1962) Extractives from Andira inermis. Journal of the Chemical Society, 4906–4909.
KissL, SzilágyiL, AntusS. (2002) A Simple Conversion of 2′-Benzyloxyflavanone to Pterocarpan. Zeitscrift fuer Naturforschung, 57b, 1165–1168.
14.
JuhászL, SzilágyiL, AntusS, VisyJ, ZsilaF, SimonyiM. (2002) New Insight into the Mechanism of Hypervalent Iodine Oxidation of Flavanones. Tetrahedron, 58, 4261–4265.
15.
GorePH. (1955) Friedel-Crafts Acylation. Chemical Reviews, 55, 229–281.
16.
AkihiroO, IwasakiY, YasuoA. (1982) Simple Preparation of Some Aryl Ethers. Synthesis, 828–829.
PrakashO, TanwarMP. (1995) Hypervalent Iodine Oxidation of Flavanones: A New Synthesis of Methyl 2-Aryl-2,3-dihydrobenzofuran-3-carboxylates by 1,2-Aryl Shift. Bulletin of Chemical Society of Japan, 68, 1168–1171.
19.
PrakashO, PahujaS, GoyalS, SawhneySN, MoriartyRM (1990) 1,2-Aryl Shift in the Hypervalent Iodine Oxidation of Flavanones: A New Useful Synthesis of Isoflavones. Synlett, 337–338.
