Treatment of 4- and 5-alkynylamines with 0.5-1.2 equiv. of butyllithium brought about a facile anionic cyclization, giving the corresponding enamine pyrrolidines and piperidines having an exo double bond in high yields. Treatment of 4-alkynamides with lithium aluminum hydride also gave the similar enamine pyrrolidines in high yields.
TOKUDA, MASAO;FUJITA, HIROTAKE;SUGINOME, HIROSHI, TETRAHEDRON LETT., 31,(1990) N7, C. 5353-5356