Aminium Salts Induced Desulphurization of Allyl and Diallyl Thiiranes. Synthesis of Dienes and Trienes
作者:Vincenzo Caló、Luigi Lopez、Angelo Nacci、Giuseppe Mele
DOI:10.1016/0040-4020(95)00502-y
日期:1995.8
conversion of methylene chloride in solutions of several allyl and diallyl episulphides 1–6 into the corresponding unsaturated derivatives 7–12. The desulphurization process, which occurs through a plausible chain electron-transfer mechanism, rapid and may proceed in a fashion that preserves the stereochemistry of the starting episulphide.
alpha-Ketosulphides of benzothiazole 1 react with allylic carbonates in the presence of palladium acetate in dichloromethane under mild conditions affording alpha,alpha-diallylated ketosulphides 2 in high yields. Reduction of 2 with sodium borohydride in isopropanol gives episulphides which in turn can be transformed almost quantitatively into trienes.
Allylated ketosulphides of benzothiazole as intermediates for stereoselective synthesis of allyl ketones, allyl thiiranes and dienes
dichloromethane under mild conditions affording α- and α,α-diallylated ketosulphides 2 in high yields. Reductive desulphurization of 2a–d with tributyltin hydride gives diallylated ketones 3a–d, whereas reduction of mono-allylated 2e–k with sodium borohydride in isopropanol affords allyl episulphides 4e–k prevalently as (Z)-isomers which can be transformed stereoselectively into dienes.