Regioselective Cu(i)-catalyzed intramolecular hydroacylation and dimerization of propargylarylaldehydes

We present the details of the formation of regioselective C-C bonds from propargyl arylaldehydes. The readily available CuSO₄·5H₂O salt could promote regioselective intramolecular hydroacylation and head-to-head additive dimerization of propargyl aryl aldehydes in the presence of a catalytic amount of ascorbic acid. The transformations do not require any bases during the course of the reaction. In both transformations, substrates bearing electron-donating groups on the aryl ring are more compatible with the reaction conditions, providing the corresponding coupling products with good yields. In addition, the presented catalytic system shows high regioselectivity control for different substituents regardless of their polarity.