N-Heterocyclic Carbene-Mediated Enantioselective Addition of Phenols to Unsymmetrical Alkylarylketenes

✍ Scribed by Carmen Concellón; Nicolas Duguet; Andrew D. Smith

• Book ID: 101426000
• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 282 KB
• Volume: 351
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200900538

✦ Synopsis

Abstract

Chiral N‐heterocyclic carbenes (NHCs) mediate the enantioselective addition of 2‐phenylphenol to unsymmetrical alkylarylketenes, delivering α‐alkyl‐α‐arylacetic acid derivatives with good levels of enantiocontrol (up to 84% ee). Enantiodivergent stereochemical outcomes are observed using 2‐phenylphenol and benzhydrol in the NHC‐promoted esterification reaction using a triazolium precatalyst derived from pyroglutamic acid, consistent with distinct mechanistic pathways operating within these processes.