Practical by Ligand Design: A New Class of Monodentate Phosphoramidite Ligands for Rhodium-Catalyzed Enantioselective Hydrogenations

✍ Scribed by Baoguo Zhao; Zheng Wang; Kuiling Ding

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 270 KB
• Volume: 348
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200606013

✦ Synopsis

Abstract

A new class of low‐cost and easy‐to‐prepare monodentate phosphoramidite ligands (CydamPhos) has been developed from readily accessible and cheap trans‐1,2‐diaminocyclohexane as starting material through a three‐step transformation. This type of ligands exhibited excellent enantioseletivities and high activities in rhodium(I)‐catalyzed asymmetric hydrogenations of dehydro‐α‐amino acid methyl esters 9 (ee: 96.2–99.8 %) and acetylenamides 11 (91.8–98.8 %). The remarkable substituent effects exhibited by the ligands on the enantioselective control of the catalysis are rationalized on the basis of molecular structure of the catalyst precursor.