Alkylation of phenylglycinol-derived oxazolopiperidone lactams. Enantioselective synthesis of beta-substituted piperidines.
The stereochemical outcome of the alkylation of a variety of phenylglycinol-derived oxazolopiperidone lactams is studied. The influence of the configuration of the C-8a stereocenter and the effect of the substituents at the C-8 and C-8a positions on the stereoselectivity of the reaction are discussed. The synthetic utility of these alkylation reactions is illustrated with the synthesis of cis and trans 3,5-disubstituted, 2,5-disubstituted, and 2,3,5-trisubstituted enantiopure piperidines, and the indole alkaloids 20R- and 20S-dihydrocleavamine.
Amat
Mercedes
M
Laboratory of Organic Chemistry, Faculty of Pharmacy, University of Barcelona, 08028-Barcelona, Spain. amat@ub.edu
Escolano
Carmen
C
Lozano
Oscar
O
Gómez-Esqué
Arantxa
A
Griera
Rosa
R
Molins
Elies
E
Bosch
Joan
J