Asymmetric synthesis XIV: A short and efficient synthesis of 3,5-disubstituted pyrrolizidine alkaloids via the CN(R,S) method

Abstract

The enantiospecific synthesis of the dextrorotatory enantiomer of the ant venom alkaloid 3-heptyl-5-methylpyrrolidine 11 has been achieved in four steps and 31% overall yield from the chiral 2-cyano-5-oxazolopyrrolidine synthon 4 . On the basis of previous results it was concluded that the absolute configuration of + 11 is 3S, 5R, 8S in disagreement with an earlier report.