Catalytic Acceptorless Dehydrogenation of Aliphatic Alcohols

摘要

Oxidation of alcohols to produce carbonyl compounds is a fundamentally importantchemical process.Catalytic acceptorless dehydrogenation (CAD) of alcohols is one of the mostideal classes of this reaction releasing molecular hydrogen as a sole side product.Moreover,CAD is an attractive transformation for hydrogen storage.Although CAD of alcohols by atransition metal complex was developed,typically,harsh reaction conditions (>100C or UVirradiation) were required.1 It was due to thermodynamic difficulty about this process.Despitethis difficulty,recently,several reports using the combination of a photoredox catalyst and atransition metal catalyst achieved CAD of alcohols under visible light irradiation at roomtemperature.2 Although they achieved mild CAD reactions,scopes of these examples werelimited to benzylic alcohols which were more reactive than aliphatic alcohols.On the otherhand,recently,we developed several hybrid catalyst systems comprising a photoredox catalyst,an organocatalyst and a metal catalyst.3 Based on this concept,we envisioned the ternary hybridcatalyst system to achieve CAD of aliphatic alcohols under visible light irradiation at roomtemperature.