Stereoselective synthesis of 1,4-dienes by chelation-controlled reduction of benzothiazole β-oxosulfides
摘要:
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.
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.
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.