Stereoselective synthesis of new chiral N-tertiary tetrasubstituted beta-enamino ester piperidines through an ammonia-catalyzed process.
We report here two approaches for the preparation of new N-substituted beta-enamino ester piperidines featuring an exocyclic tetrasubstituted double bond, based either on the direct alkylation of piperidine beta-enamino esters bearing an exocyclic trisubstituted double bond or on the intramolecular cyclization of linear amino beta-keto esters. The target compounds were obtained as unusual (Z)-stereoisomers in high yields. The key role of ammonia as reagent, acting both as a nucleophile and a base, was underlined. The diastereoselective formation of the products was rationalized on the basis of an ammonia addition-syn elimination catalytic process.
Université Pierre et Marie Curie, Institut de Chimie Moléculaire FR 2769, Laboratoire de Chimie Organique, UMR 7611, Equipe de Chimie des Hétérocycles, 4 Place Jussieu, 75252 Paris Cedex 05, France.
Sandrine
S
Calvet-Vitale
Corinne
C
Vanucci-Bacqué
Marie-Claude
MC
Fargeau-Bellassoued
Gérard
G
Lhommet
D000641:Ammonia / Q000737:chemistry*; D002384:Catalysis; D004952:Esters; D010880:Piperidines / Q000138:chemical synthesis*; D013237:Stereoisomerism
D004952:Esters; D010880:Piperidines; D000641:Ammonia