New and efficient approaches to the semisynthesis of taxol and its C-13 side chain analogs by means of β-lactam synthon method
作者:Iwao Ojima、Ivan Habus、Mangzhu Zhao、Martine Zucco、Young Hoon Park、Chung Ming Sun、Thierry Brigaud
DOI:10.1016/s0040-4020(01)91210-4
日期:1992.1
Highly efficient chiral ester enolate-imine condensation giving 3-hydroxy-4-aryl-β-lactams with excellent enantiomericpurity is successfully applied to the asymmetric synthesis of the enantiomerically pure taxol C-13 side chain, N-benzoyl-(2R,3S)-3-phenyl-isoserine and itsanalogs. (3R,4S)-N-benzoyl-3-(1-ethoxyethoxy)-4-phenyl-2-azetidinone readily derived from the 3-hydroxy-4-phenyl-β-lactam is coupled
Asymmetric synthesis of β-lactams by chiral ester enolate - imine condensation
作者:Iwao Ojirna、Ivan I-Iabus
DOI:10.1016/s0040-4039(00)97603-2
日期:1990.1
Asymmetric cyclocondensation of N,N-bis(silyl)glycinates bearing chiral ester moieties with aldimines is found to proceed with extremely high enantioselectivity to give the corresponding chiral β-lactams in good to high yields. It is found that the E/Z-geometry of the chiral ester-enolate ts responsible for cis/trans stereochemistry of the β-lactam formed. Effects of various chiral auxiliaries in the
N,N-Dialkylhydrazones as the Imine Component in the Staudinger-Like [2+2] Cycloaddition to Benzyloxyketene We thank the Dirección General de Investigación Científica y Técnica (grants BQU 2001-2376 and PPQ 2000-1341) and the Junta de Andalucía for financial support. We also thank the Ministerio de Educación y Ciencia for a doctoral fellowship to A.F.
作者:Rosario Fernández、Ana Ferrete、José M. Lassaletta、José M. Llera、Eloísa Martín-Zamora
OJIMA, IWAO;HABUS, IVAN, TETRAHEDRON LETT., 31,(1990) N0, C. 4289-4292
作者:OJIMA, IWAO、HABUS, IVAN
DOI:——
日期:——
Studies on Stereoselective [2+2] Cycloadditions between N,N-Dialkylhydrazones and Ketenes
作者:Eloísa Martín-Zamora、Ana Ferrete、José M. Llera、Jesús M. Muñoz、Rafael R. Pappalardo、Rosario Fernández、José M. Lassaletta
DOI:10.1002/chem.200400452
日期:2004.12.3
chiral, non-racemic N,N-dialkylhydrazones 1 and functionalized ketenes constitute an efficient methodology for the stereoselective construction of the beta-lactam ring. The potential for fine tuning of the dialkylamino auxiliary structure, the availability of a high-yielding deprotection method for the release of the free azetidinones, and the high thermal and chemical stability of hydrazones as N-dialkylamino