Synthetic transformation of homopropargylic selenides to conjugated diene-substituted alcohols and amines using diisopropoxy(η~2- alkyne)titanium intermediates

摘要

The reaction of homopropargylic selenides with the low-valent titanium reagent, derived from Ti(O-i-Pr)_4 and 2 equiv of i-PrMgCl, proceeded via titanium-alkyne complexes, followed by the reaction with electrophiles, such as aldehydes and imines to afford allylic alcohols and amines having a phenylseleno group in moderate to high yields with excellent regioselectivity (up to >99:1). Especially, the reaction of the silyl-substituted alkynes with imines provided the desired products in almost complete regioselectivity. The resulting products were subjected to oxidation with H_2O_2 to lead conjugated diene-substituted alcohols and amines via selenoxide elimination in high yields. In addition, the isomer ratio of products was nearly completely maintained under the oxidative deselenation conditions.