Tandem Cyclization of Alkynylmetals Bearing a Remote Leaving Group via Cycloalkylidene Carbenes.
Treatment of terminal alkynes bearing a remote leaving group with MNR(2) (M = Li, Na, K) gives bicyclo[n.3.0]-1-alkenes (n = 3, 4). The tandem cyclization proceeds through a mechanism involving exo-cyclization of an alkynylmetal intermediate and intramolecular C-H insertion of the resulting carbenoid.
Harada
T
Department of Chemistry, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku Kyoto 606-8585, Japan.
Fujiwara
T
Iwazaki
K
Oku
A