A highly enantioselective rhodium catalyst for the hydrogenation of aliphatic α-keto esters

✍ Scribed by Dr. Felix Spindler; Ulrich Pittelkow; Hans-Ulrich Blaser

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 529 KB
• Volume: 3
• Category: Article
• ISSN: 0899-0042
• DOI: 10.1002/chir.530030423

✦ Synopsis

The enantioselective hydrogenation of several a-keto acid derivatives with rhodium diphosphine catalysts has been investigated using a random screening approach. The neutral rhodium catalyst prepared in situ from bis(2,5norbornadiene rhodium chloride) and NORPHOS has been found to be an excellent catalyst for preparing aliphatic a-hydroxy esters in high optical purities. The reaction parameters for the hydrogenation of ethyl 2-0~0-4-phenyl-butyrate, an intermediate for the ACE inhibitor Benazepril, were optimized and the best optical yields obtained were 96%.