Facile conversion of 2-azetidinones to 2-piperidones: application to a formal synthesis of Prosopis and Cassia alkaloids
摘要:
Nonracemic 5,6-disubstituted 2-piperidones were prepared from readily accessible 3,4-disubstituted-2-azetidinones having pre-installed substituents by reductive ring opening of 2-azetidinones followed by stereoselective installation of Z-alpha,beta-unsaturated ester and lactam formation. For the synthetic application to the naturally occurring piperidine alkaloids, such as Prosopis and Cassia alkaloids, 5-hydroxy-2-piperidones (+)-13 and (-)-24 were prepared from 2-azetidinones (-)-6b and (+)-18 via two-carbon ring homologation. (C) 2003 Elsevier Ltd. All rights reserved.
Facile conversion of 2-azetidinones to 2-piperidones: application to a formal synthesis of Prosopis and Cassia alkaloids
摘要:
Nonracemic 5,6-disubstituted 2-piperidones were prepared from readily accessible 3,4-disubstituted-2-azetidinones having pre-installed substituents by reductive ring opening of 2-azetidinones followed by stereoselective installation of Z-alpha,beta-unsaturated ester and lactam formation. For the synthetic application to the naturally occurring piperidine alkaloids, such as Prosopis and Cassia alkaloids, 5-hydroxy-2-piperidones (+)-13 and (-)-24 were prepared from 2-azetidinones (-)-6b and (+)-18 via two-carbon ring homologation. (C) 2003 Elsevier Ltd. All rights reserved.