1.
J Org Chem
; 70(21): 8352-63, 2005 Oct 14.
Artigo
em Inglês
| MEDLINE
| ID: mdl-16209578
RESUMO
Three natural pyrrolizidines, (+)-amphorogynines A and D and (+)-retronecine, have been prepared from a common lactam intermediate. This central compound, in turn, was synthesized in diastereomerically enriched form through a highly selective [2 + 2]-cycloaddition of dichloroketene with a chiral enol ether, followed by Beckmann ring expansion and reduction. Subsequent stereocenters were then cleanly introduced through internal induction.