Chemoenzymatic formal total synthesis of (−)-bestatin
摘要:
A highly stereoselective, enzymatic reduction of an alpha-chloro-beta-keto ester provided the key intermediate for a total synthesis of the alpha-hydroxy-beta-amino acid moiety of (-)-bestatin. The reduction product was cyclized to a glycidic ester that was opened in a Ritter reaction with benzonitrile, affording a trans-oxazoline, which was hydrolyzed under acidic conditions to the target molecule. (C) 2005 Elsevier Ltd. All rights reserved.
Synthesis and Reactions of 3-(Nosyloxy)-2-keto Esters
摘要:
A series of 3-(nosyloxy)-2-keto esters 7a-j were prepared from the corresponding cr-keto esters by conversion to the trimethylsilyl enol ether and reaction with p-nitrobenzenesulfonyl peroxide. Conversion of these materials to 1,2,3-trifunctionalized compounds is described, and comparison of their properties with isomeric 2-(nosyloxy)-3-keto esters is discussed.
An Asymmetric Catalytic Darzens Reaction between Diazoacetamides and Aldehydes Generates<i>cis</i>-Glycidic Amides with High Enantiomeric Purity
作者:Wei-Jun Liu、Bing-Da Lv、Liu-Zhu Gong
DOI:10.1002/anie.200903061
日期:2009.8.17
strength: The title reaction was catalyzed by a chiral titanium complex formed in situ from commercially available Ti(OiPr)4 and (R)‐binol, and gave cis‐glycidic amides with excellent enantiomeric purity (see scheme). This new method has been applied to the preparation of chiralbuildingblocksused for the synthesis of the side chain of taxol and (−)‐bestatin.
钛强度:标题反应是由由市售Ti(O i Pr)4和(R)-比诺醇原位形成的手性钛络合物催化的,得到具有出色对映体纯度的顺式-缩水甘油酰胺(参见方案)。此新方法已应用于制备用于合成紫杉醇和(-)-bestatin侧链的手性结构单元。