Phosphine-catalyzed one-pot isomerization of 3-alkynoates and [2+3]-cycloaddition with imines: formal synthesis of Securinega alkaloid (+/-)-allosecurinine

Trimethylphosphine-induced isomerization and cycloaddition of 3-alkynoates with imines for the synthesis of 2,5-syn di-substituted pyrrolines were described. In addition, the utility of this protocol was demonstrated in the efficient formal synthesis of the Securinega alkaloid 'allosecurinine'.