Novel Approach to the Synthesis of Asymmetric 2-Aryltetralones

Significance

A novel rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to naphthoquinone monoketals affords 2-aryltetralones in high yields and excellent ee values. Various arylboronic acids can be used including electron-withdrawing, electron-donating, o-tolyl, 2-naph­thyl, and 3-thienyl boronic acids. If the monoketal is substituted with a methylenedioxy group, the reaction is slower and requires higher catalyst loading. Asymmetric alkenylation is also possible with both unsubstituted and substituted alkenylboronic species. Quinone monoketals can also be used as substrates, although the yields from these reactions are slightly lower. The α-tetralones can be converted into the synthetically desirable α-aryl ketones, as demonstrated by the conversion of these products into a key intermediate for the synthesis of a family of alkaloids.