A new general synthesis of 3- and 3,4-substituted 4a–q, 3,4-annelated 7a–d and condensed tricyclic 9a–e thiophenes has been developed through Simmons-Smith reaction on the respective α-oxoketene dithioacetals. Extension of the reaction to α-cinnamoylketene dithioacetals 10a–e and its higher enyl analogs 13a–d, 15a–c gave the corresponding 3-styryl 11a–e and 3-di- and trienyl 14a–d, 16a–c thiophenes
Samarium diiodide-promoted reductive cleavage of carbon-sulfur bonds: a novel stereoselective generation of functionalized vinylsamarium species and synthesis of .beta.-thiobutenolides
(Alkoxycarbonyl)ketene dithioacetals are cleanly reduced by SmI2 to provide a new and efficient method for the stereoselective generation of the corresponding novel highly functionalized vinylsamarium species which react with a proton, allyl bromide, and aldehydes to give the corresponding reduction products, allylation products, and beta-thiobutenolides, respectively.
A Novel and Efficient Generation of Functionalized Vinylcopper Reagents and their Reactions with Electrophiles. Synthesis of β-Methylthiobutenolides
作者:Makoto Hojo、Hajime Harada、Akira Hosomi
DOI:10.1246/cl.1994.437
日期:1994.3
amounts of dimethylcuprate derived from methyllithium and cuprous cyanide to yield the corresponding functionalized vinylcopper species. These organocopper species are efficiently trapped by carbon electrophiles. Formal substitution reactions of a methylthio group in ketene dithioacetals by electrophiles can be attained by one-pot operation. Synthesis of β-thiobutenolides was also achieved.
beta,beta-Bis(methylthio)vinyl carbonyl compounds (1) reacted with pyridine-6HF and Hg(OCOCF3)(2) to give beta,beta-difluoro-beta-(methylthio) carbonyl compounds (2) in good yield. (C) 2000 Elsevier Science S.A. All rights reserved.