pH-Selective Isolation of Alkynyl,Acyl,and Ketonyl Intermediates in anti-Markovnikov and Markovnikov Hydration of a Terminal Alkyne Catalyzed by an Iridium Aqua Complex

摘要

Isolation of an alkynyl intermediate [Cp~*Ir~(III)(bpy)CCPh]~+ (2,Cp = eta~5-C_5Me_5,bpy = 2,2'-bipyridine) and an acyl intermediate [Cp~*Ir~(III)(bpy)C(O)CH_2Ph]~+ (3) in anti-Markovnikov hydration of phenylacetylene and a ketonyl intermediate [Cp~*Ir~(III)(bpy)CH_2C(O)Ph]~+ (4) in Markovnikov hydration of phenylacetylene has been achieved by controlling pH of the aqueous solution.The structures of 2,3,and 4 were determined by electrospray ionization mass spectrometry (ESI-MS),~1H NMR,and X-ray analysis.