Solid-phase synthesis of pyrrolidines via 2-azaallyl anion cycloadditions with alkenes

The preparation of a variety of highly substituted pyrrolidines was achieved by solid-phase synthesis through the [2 pi s + 4 pi s] cycloaddition of 2-azaallyl anions with alkenes. Resin-bound aldehydes 2 were condensed with a-amino stannanes 3 to afford (2-azaallyl)stannanes 4. Transmetalation of 4 with n-BuLi in the presence of electron-rich alkenes followed by the addition of an electrophile provided the polymer-bound pyrrolidines 7. The free pyrrolidines 9-23 were obtained upon cleavage from the solid support. (C) 1997 Elsevier Science Ltd.