Azomethine ylides from tin-substituted cyclic carbinol amides: a new route to highly substituted pyrrolizidines.

Addition of organolithium and organomagnesium reagents to N-(tri-n-butylstannylmethyl)phthalimides yields N-(tri-n-butylstannylmethyl) cyclic carbinol amides, which form azomethine ylides upon treatment with HF·pyridine. This novel route to azomethine ylides allows rapid access to highly functionalized pyrrolizidines (1,2,3,9b-tetrahydropyrrolo[2,1-a]isoindol-5-ones).