Abstract Methods for the preparation of substituted homoallylic amines and their conversion to pyrrolidines or pyrrolizidines are described. N-Alkylation of a variety of homoallylic secondary amines with (tributylstannyl) methyl methanesulfonate and subsequent tin-lithium exchange, generates organolithium species that undergo intramolecular carbolithiation (anionic cyclization). High stereoselectivities in the cyclization, particularly for the ...