Y. Bousquet, P. C. Anderson, T. Bogri
Nov 17, 1997
Citations
0
Influential Citations
15
Citations
Journal
Tetrahedron
Abstract
Abstract Two approaches to enantiopure 4-oxo- and 4-( R )-hydroxypipecolic acid derivatives from protected L-aspartic acid were developed. The first route exploits an intramolecular Michael addition on the stable enaminone 8 . Hydrogenation and concomitant decarboxylation gave the 4-oxo derivative 11 which was reduced selectively to the 4-( R )-hydroxy derivative 12 . The second route starts with a Michael addition followed by an intramolecular Dieckmann condensation to build the piperidine ring. The 4-oxo derivatives 11 and 19 are thus obtained in an expeditious manner on large scale without any chromatographic purification. Both sequences proved to be highly stereoselective.