New technical synthesis of ethyl (R)-2-hydroxy-4-phenylbutyrate of high enantiomeric purity

Authors
Herold, P Indolese, AF Studer, M Jalett, HP Siegrist, U Blaser, HU
Citation
P. Herold et al., New technical synthesis of ethyl (R)-2-hydroxy-4-phenylbutyrate of high enantiomeric purity, TETRAHEDRON, 56(35), 2000, pp. 6497-6499
Citations number
11
Categorie Soggetti
Chemistry & Analysis","Organic Chemistry/Polymer Science
Journal title
TETRAHEDRON
ISSN journal
00404020 → ACNP
Volume
56
Issue
35
Year of publication
2000
Pages
6497 - 6499
Database
ISI
SICI code
0040-4020(20000825)56:35<6497:NTSOE(>2.0.ZU;2-F
Abstract
A new technical synthesis to produce ethyl (R)-2-hydroxy-4-phenylbutyrate ( 5), an important intermediate for several ACE inhibitors with >99% ee in an over-all yield of 50-60% is described starting from acetophenone and dieth yl oxalate. Key step is the chemo- and enantioselective hydrogenation of et hyl 2,4-dioxo-4-phenylbutyrate (6) (ee up to 86%) catalyzed by a heterogene ous Pt catalyst modified with dihydrocinchonidine, followed by crystallizat ion of the 2-hydroxy-4-oxo ester 7 and hydrogenolysis of the 4-keto group. (C) 2000 Elsevier Science Ltd. All rights reserved.