Baker's Yeast-Mediated Reductions of α-Keto Esters and an α-Keto-β-Lactam. Two Routes to the Paclitaxel Side Chain
作者:Margaret M. Kayser、Marko D. Mihovilovic、Jeff Kearns、Anton Feicht、Jon D. Stewart
DOI:10.1021/jo9900681
日期:1999.9.1
the case of ethyl benzoylformate, the addition of methyl vinyl ketone increased the enantioselectivity of the reduction. These reductions were applied to two syntheses of the paclitaxel C(13) side chain [(2R,3S)-N-benzoyl-3-phenylisoserine]. In the first, a racemic alpha-keto-beta-azido ester was reduced by whole cells of Baker's yeast to afford a diastereomeric mixture in which the desired product
The dynamic kinetic resolution of 3-oxo-4-phenyl-β-lactam by recombinant E. coli overexpressing yeast reductase Ara1p
作者:Yan Yang、Melissa Drolet、Margaret M. Kayser
DOI:10.1016/j.tetasy.2005.07.029
日期:2005.8
Using a recombinant E coli strain overexpressing yeast reductase Ara 1 p, we reduced racemic 3-oxo-4-phenyl-beta-lactam to cis-(3S,4R)-3-hydroxy-4-phenyl-beta-lactam as a single enantiopure product. The dynamic kinetic resolution occurred over the course of fermentation at pH 7. Under the same conditions, 3-oxo-4-(2-thiophenyl)-beta-lactam 4 and 3-oxo-4-(2-furyl)-beta-lactam 5 were not resolved. (c) 2005 Elsevier Ltd. All rights reserved.
Application of newly available bio-reducing agents to the synthesis of chiral hydroxy-β-lactams: model for aldose reductase selectivity
作者:Margaret M. Kayser、Melissa Drolet、Jon D. Stewart
DOI:10.1016/j.tetasy.2005.11.008
日期:2005.12
Homochiral 3-hydroxy-4-substituted beta-lactams serve as precursors to the corresponding a-hydroxy-p-amino acids-key components of many biologically and therapeutically important compounds. We have developed a short synthetic sequence for these targets using a biocatalytic reduction to install the desired chirality. By employing 3-oxo-4-phenyl-beta-lactam as a probe, 19 individual yeast reductases were screened for their efficiency and enantioselectivity with respect to this substrate. Four highly selective candidates all belonging to the aldose reductase (AKR) superfamily were identified. Two are Re-face selective and two are Si-face selective. The modelled three-dimensional structures of these enzymes provide a rationale for this behaviour and suggest strategies for their further improvement. (c) 2005 Elsevier Ltd. All rights reserved.
Enantiopure α-hydroxy-β-lactams via stereoselective glycosylation
作者:Bimal K. Banik、Maghar S. Manhas、Ajay K. Bose
DOI:10.1016/s0040-4039(97)01130-1
日期:1997.7
derivative had to be employed for this reaction since a glucal derivative failed to work. This synthesis complements our previously described preparation of the corresponding cis isomers by the same methodology. Thus, convenient access has become available to all four homochiral stereoisomers of α-hydroxy-β-lactams some of which are synthons for Taxol® and analogs.