Regiochemical and stereochemical studies on halogen-induced ring expansions of unsaturated episulfides
摘要:
The reactions of unsaturated episulfides with bromine and iodine have been studied. Initially produced in the reaction is a ring opened sulfenyl halide intermediate, which in the presence of the carbon-carbon double bond or triple bond cyclizes to beta,beta'-dihalo sulfide cycloadducts. The regiochemistry and relative stereochemistry of these cyclizations have been examined as a function of the length of the tether between the episulfide moiety and the unsaturated functionality, the presence of alkyl substituents, and the type of unsaturation. A discussion of the mechanistic and stereochemical features of the ring-expansion process is presented.
Alkyltitanium alkoxides generally serve as nucleophiles in reactions with carbonyl compounds and cross-coupling. Their application as reductants is known but remains underdeveloped. Here, we report that irradiation with visible light makes these organometallic compounds efficient reducing agents for the dehalogenation of 1,2- and 1,3-haloalcohols. This reaction was utilized for the reduction of epoxides
Malinovskii,M.S.; Khmel',M.P., Journal of Organic Chemistry USSR (English Translation), 1967, vol. 3, p. 1748 - 1749
作者:Malinovskii,M.S.、Khmel',M.P.
DOI:——
日期:——
σ–π Chelation-controlled chemoselective ring openings of epoxides
作者:Naoki Asao、Taisuke Kasahara、Yoshinori Yamamoto
DOI:10.1016/s0040-4039(01)01669-0
日期:2001.10
The chemoselective ring opening of alkynyl epoxides in the co-existence of the corresponding alkyl epoxides is achieved in the Me3Al mediated reaction with alkynyllithium reagents. The observed interesting chemoselectivity is most probably a reflection of bidentate complexation of the Lewis acid to an n-electron of an oxygen atom of the epoxide and pi -electrons of the C C triple bond. (C) 2001 Elsevier Science Ltd. All rights reserved.
Perveev,F.Ya.; Gonoboblev,L.N., Journal of Organic Chemistry USSR (English Translation), 1967, vol. 3, p. 2196