C-C Cross-Coupling of Alcohols Catalyzed by Ag/Al₂O₃

Key words

C-C bond formation - alcohols - γ-alumina - silver

Significance

γ-Alumina-supported silver clusters (Ag/Al₂O₃) catalyzed the C-C bond formation of secondary alcohols 1 and primary alcohols 2 in the presence of Cs₂CO₃ to give the corresponding ketones 3 in 51-81% yield (12 examples). The catalyst was recovered by filtration and reused twice without significant loss of activity after the reactivation (e.g., formation of 3a; 1^st reuse: 77%, 2^nd reuse: 78%).

Comment

The authors have previously reported the preparation of Ag/Al₂O₃ and its application to dehydrogenation of alcohols (Chem. Eur. J. 2009, 15, 2341). The authors proposed a reaction pathway for the present coupling as follows: (1) dehydrogenation of 1 and 2 forming the corresponding ketone and aldehyde along with co-production of Ag-H; (2) dehydrative cross-aldol reaction giving α,β-unsaturated ketone; (3) reduction of the C=C bond to give 3.