Benzotriazolylmethylaminosilanes, readily accessible from the reaction
of benzotriazole, an aldehyde and an (aminomethyl)silane in water at
20 degrees C, are azomethine ylide equivalents which undergo stereospe
cific cycloadditions with dipolarophiles to give substituted pyrrolidi
nes or 25-dihydropyrroles in good yields.