Journal of Chemical Research

The electrophilic properties associated with iodine have been exploited in recent years to effect α-halogenation of carbonyl compounds and their α,β-unsaturated derivatives. In this review, molecular iodine is presented as a readily-available and easy-to-handle reagent to effect α-halogenation of carbonyl compounds in the presence or absence of catalysts.

Tetrasubstituted olefins containing a 1,4-diene structural unit can be regio- and stereoselectively synthesised in good yields under mild conditions, in one pot, by Michael addition of phenylselenomagnesium bromide to acetylenic sulfones, followed by coupling with allylic bromides.

Nucleophilic carbene-catalysed oxidative esterification of aldehydes with alcohols and phenols without additional oxidant under an air atmosphere has been achieved, which provides a metal-free new methodology for the oxidative esterification of aldehydes.

An efficient method for the synthesis of 1,2,4,5-tetrasubstituted imidazoles by three-component condensation of benzil, benzonitrile derivatives and primary amines under solvent-free conditions using molecular iodine as catalyst is described with high product yields. The significant features of the iodine-catalysed condensation are operational simplicity, inexpensive reagents, high yield of products and use of non-toxic reagents.

Porous polymer based on copolymer of acrylonitrile and the ionic liquid 1-allyl-3-methylimidazolium can be prepared by free radical polymerisation and then turned into porous particle by a two-step swelling method. The CO₂ absorption of the product was investigated.

A series of (Z)-13-(arylimino)-12,13-dihydro-5H-benzo[e]naphtho[2,3-b][1,4]diazepine-6,11-dione derivatives have been synthesised by one pot cyclisation in good yield via electron donor–acceptor complexes by reacting 2-aminoarylbenzimidamides with 2,3-dichloro-1,4-naphthoquinone. The high yield and simplified workup procedure in addition to the mild and neutral reaction conditions are the main advantages of this approach.

N,N-dimethylformamide promoted the reaction of alkyl or arylisocyanides with barbituric acid derivatives which led to 5-[(alkyl or arylamino)methylene]barbituric acids in good yields at room temperature. The workup of reactions was very simple and the crude products were sufficiently pure to be used without further purification. This procedure provides an alternative method for the synthesis of aminomethylenebarbituric acids.

A novel molecular clip from diphenylglycoluril and phthalhydrazide has been synthesised. Its structure and conformation was confirmed by single crystal X-ray diffraction.

1,3-Dipolar cycloaddition reactions of α-chloro and simple nitrones have been studied with novel α-N-methyl/phenyl furan derivatives as new dipolarophiles. The reactions are found to be highly regioselective to afford single 5-spiro isoxazolidines with high yield in a short reaction time.

An efficient and facile synthesis of 3,5-di(hetero)aryl-1,2,4-thiadiazoles by oxidative dimerisation of thioamides by grinding with NBS under solvent-free conditions at room temperature has been developed. The efficiency of this reaction was demonstrated by the compatibility with trifluoromethyl, methyl, methoxy, chloro, pyridyl and thienyl groups. This method has notable advantages in terms of short reaction times, high yields and is a more practical alternative to the existing methods to access these compounds.

Erythrin, isolated in 7.3% yield from the lichen Roccella montagnei, was converted via a Smiles rearrangement to a series of diphenyl ethers. Those with a free carboxylic acid at C-1 underwent a novel decarboxylative oxidative cyclisation in the presence of Pd(OAc)₂ to produce 5-decarboxydibenzofurans. All compounds were assayed for their antioxidant and β-glucuronidase enzyme inhibitory activity.

Upon reaction with an excess of 2,2-dimethylpropane-1,3-diol (neopentyl glycol) under acid catalysis, estrones form 17-O-[2′,2′-dimethyl-2′-(5″,5″-dimethyl-1″,3″-dioxanyl)ethyl] substituted estra-3, 17β-diols. The reaction represents a formal reduction of a keto function under acidic conditions in the absence of a metal.

1,3-bis-(2,6-diisopropylphenyl)imidazolinium chloride (SIPr·HCl), a precursor for an N-heterocyclic carbene, was examined as a pro-ligand in C–N coupling reactions. Thus SIPr·HCl associated with a palladium catalyst was found to be efficient for the amination of aryl chlorides under mild conditions.

A study on the bromolactonisation of alkenoic acids is reported. When various pent-4-enoic acids reacted with (diacetoxyiodo)benzene (DIB) and lithium bromide in CH₃OH at room temperature, most of the five-membered bromolactones were obtained in good to excellent yields in short times. Some had two diastereoisomers. When but-3-enoic acid and trans-hex-3-enoic acid were treated under the same conditions, only unsaturated lactones were found after workup. When hex-5-enoic acid was subjected to the same conditions, however, the desired six-membered bromolactone was not successfully separated.

Immobilisation of copper acetate onto a modified polystyrene provided a polymer-supported copper(II) Schiff base catalyst, which is effective in the O-arylation reaction of phenols with aryl halides to give diaryl ethers in high yields. This catalyst is air-stable and was recycled for five times with minimal loss of activity.

Trisubstituted 1,3-dienes can be stereoselectively synthesised in one pot under mild conditions, in good yields, by the hydrostannylation of alkylarylacetylenes, followed by the Stille cross-coupling with alkenyl halides.

The adduct produced in the reaction between alkyl isocyanides and dialkyl acetylenedicarboxylates was trapped by furan-2-carboxylic acid arylidene-hydrazides to afford highly functionalised ketenimines in good yields. The reaction is characterised by mild conditions, high selectivity, and tolerance to various functional groups.