Diastereoselective reduction of β-ketophosphonates derived from amino acids. A new entry to enantiopure β-hydroxy-γ-aminophosphonate derivatives
作者:Mario Ordóñez、Ricardo de la Cruz、Mario Fernández-Zertuche、Miguel-Ángel Muñoz-Hernández
DOI:10.1016/s0957-4166(02)00159-3
日期:2002.4
The reduction of gamma-N,N-dibenzylamino-beta-ketophosphonates 4 derived from readily available (S)-tribenzylated amino acids teas achieved with catecholborane at -20degreesC affording gamma-amino-beta-hydroxyphosphonates 5 in high diastereoselectivity and good chemical yield. These reactions provide a new entry to enantiomerically pure gamma-amino-beta-hydroxyphosphonates. (C) 2002 Elsevier Science Ltd. All rights reserved.
Chemoenzymatic synthesis of ketomethylene tripeptide isosteres
A chemoenzymatic method is described for the synthesis of a desired ketomethylene tripeptide isostere. The key step is an enzymatic hydrolysis, which removes the C-terminal ester-protecting group under mild conditions without epimerizing the existing stereogenic center and produces the desired stereoisomer in high enantiomeric excess (98% de, 97% ee). The method is short with overall 15-20% yields after seven synthetic steps from readily available starting materials being obtained. (C) 2005 Published by Elsevier Ltd.