Palladium-catalysed synthesis of α-diallylated ketosulphides of benzothiazole and their transformation into diallyl thiiranes and trienes
摘要:
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.
Stereoselective synthesis of 1,4-dienes by chelation-controlled reduction of benzothiazole β-oxosulfides
作者:Vincenzo Caló、Angelo Nacci
DOI:10.1016/s0040-4039(98)00622-4
日期:1998.5
Allylated beta-oxosulfides of benzothiazole can replace beta-oxophosphane oxides to provide a stereospecific alkene synthesis. These sulfides, by reduction with sodium borohydride afford predominantly syn beta-hydroxy sulfides. DIBAL reduction in the presence of magnesium bromide improves the syn stereomer formation. Base treatment of these beta-hydroxy sulfides affords (Z)-allyl thiiranes which are converted into (E, Z)-dienes. (C) 1998 Elsevier Science Ltd. All rights reserved.
Palladium-catalysed synthesis of α-diallylated ketosulphides of benzothiazole and their transformation into diallyl thiiranes and trienes
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.