Читать книгу Catalytic Asymmetric Synthesis - Группа авторов - Страница 31

Ishikawa reported a domino Michael reaction/hemiacetal formation/dehydration for the synthesis of C4‐alkyl substituted chiral piperidines using diphenylprolinol silyl ether (Eq. 1.31) [59]. This is a formal aza [3+3] cycloaddition reaction with aliphatic α,β‐unsaturated aldehydes and thioamide derivatives. Thioamide is a reactive nucleophile. The reaction proceeded efficiently, and only 0.1 mol % catalyst loading is sufficient for a multigram‐scale synthesis to complete within a suitable reaction time. This reaction was applied to the total synthesis of several alkaloids such as α‐skytanthine [59a] and quinine [59b].

(1.31)