Ruthenium‐Catalyzed Enantioselective Hydrogenation/Lactonization of 2‐Acylarylcarboxylates: Direct Access to Chiral 3‐Substituted Phthalides

Highly enantioselective tandem hydrogenation/lactonization of various 2‐acylarylcarboxylates including 2‐aroylarylcarboxylates were realized by using [RuCl(benzene)( S )‐SunPhos]Cl as the catalyst under mild reaction conditions. Excellent enantioselectivities (up to 99.6 % ee ) and activities (S/C=1000) were obtained. This convenient and practical method enables a direct access to a series of highly optically pure 3‐substituted phthalides that are very important molecules as valuable pharmacological compounds and diversified synthons for medicinal chemistry. Moreover, a gram‐scale reaction was performed to further demonstrate the practicality of this approach.