We have recently described the first synthetically viable route to nonstabilized iminium ylides, as well as their 1, 3-dipolar cycloadditions to give pyrrolines.'This study is now extended to construction of the pyrrolizidine nucleus, culminating in an efficient, stereospecific synthesis of retronecine (l). 233 Derivatives of retronecine are of some interest as antitumor agentsS4 Although the simplest conceivable route to pyrrolizidines appeared ...
[Kramarova, E. P.; Shipov, A. G.; Orlova, N. A.; Artamkina, O. B.; Belavin, I. Yu.; Baukov, Yu. I. J. Gen. Chem. USSR (Engl. Transl.), 1988 , vol. 58, # 5 p. 1093 - 1102,970 - 979]