Base‐mediated cyclization of 3‐[2‐(2‐oxo‐2‐phenylethyl)‐1‐pyrrolidinyl]propanenitrile to 7‐phenyl‐1,2,3,7,8,8a‐hexahydroindolizine‐6‐carbonitrile: what lies between?
Garreth L. Morgans; Manuel A. Fernandes; Willem A. L. van Otterlo; Joseph P. Michael
Three intermediates along the reaction path by which 3‐[2‐(2‐oxo‐2‐phenylethyl)‐1‐pyrrolidinyl]propanenitrile is converted into the rel‐(7R,8aR)‐ and (7R,8aS)‐diastereoisomers of 7‐phenyl‐1,2,3,7,8,8a‐hexahydroindolizine‐6‐carbonitrile upon treatment with potassium tert‐butoxide were isolated and characterized. They include the rel‐(6R,7R,8aR)‐ and (6R,7S,8aS)‐diastereoisomers of 7‐hydroxy‐7‐phenyloctahydroindolizine‐6‐carbonitrile (the former obtained as a monohydrate), and 7‐phenyl‐1,2,3,5,8,8a‐hexahydroindolizine‐6‐carbonitrile. The alcohol intermediates and the final products were also characterized by X‐ray crystallography.