Work

Aerobic Dehydrogenation of Cyclohexanone to Cyclohexenone Catalyzed by Pd(DMSO) 2 (TFA) 2 : Evidence for Ligand-Controlled Chemoselectivity

Year: 2013

Type: article

Abstract: The dehydrogenation of cyclohexanones affords cyclohexenones or phenols via removal of 1 or 2 equiv of H2, respectively. We recently reported several Pd(II) catalyst systems that effect aerobic dehydrogenation of cyclohexanones with different product selectivities. Pd(DMSO)2(TFA)2 is unique in its high chemoselectivity for the conversion of cyclohexanones to cyclohexenones, without promoting subsequent dehydrogenation of cyclohexenones to phenols. Kinetic and mechanistic studies of these reactions reveal the key role of the dimethylsulfoxide (DMSO) ligand in controlling this chemoselectivity. DMSO has minimal kinetic influence on the rate of Pd(TFA)2-catalyzed dehydrogenation of cyclohexanone to cyclohexenone, while it strongly inhibits the second dehydrogenation step, conversion of cyclohexenone to phenol. These contrasting kinetic effects of DMSO provide the basis for chemoselective formation of cyclohexenones.

Source: Journal of the American Chemical Society

DOI: 10.1021/ja4031648

Authors: Tianning Diao, Doris Pun, Shannon S. Stahl

Institution: University of Wisconsin–Madison

Language: English

Topic: Oxidative Organic Chemistry Reactions

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funder: National Institute of General Medical Sciences

Award: Bioinspired Oxidation of Organic Molecules with Organic (Co-)Catalysts