Chirospecific synthesis of trans-2,5-disubstituted pyrrolidines via stereoselective addition of organocopper reagents to N-acyliminium ions

Article abstract of DOI:10.1016/S0040-4020(01)87047-2

Reaction of the N-acyliminium ion precursor 1a (derived from S-proline via anodic methoxylation) with RCu in the presence of BF₃·Et₂O gives preferentially the trans adducts 2 (trans:cis ≥96:4). Using such a procedure, a general synthetic route to (2R, 5R)-trans-2,5-dialkylpyrrolidines has been developed, as exemplified by the chirospecific syntheses of the ant feromones trans 5-butyl-2-heptylpyrrolidine (10a), trans-5-ethyl-2-heptylpyrrolidine (10b) and trans-5-heptyl-2-(5-hexenyl)pyrrolidine (10c).