Potassium carbonate-promoted stereospecific 5-endo-trig cyclization of unactivated allenes in the absence of any transition metals.
Formation of 3-pyrrolines from simple unactivated allenes bearing a protected amino group under basic conditions is described. Treatment of alpha-amino allenes with potassium carbonate in DMF under reflux in the absence of any transition-metal catalysts gave the corresponding 3-pyrrolines in good to excellent yields, by 5-endo-trig mode cycloisomerization. The reaction of internal allenes with an axial chirality afforded the corresponding 3-pyrrolines in a stereoselective manner.
Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan. hohno@pharm.kyoto-u.ac.jp
Hiroaki
H
Ohno
Yoichi
Y
Kadoh
Nobutaka
N
Fujii
Tetsuaki
T
Tanaka