Lewis acid-catalyzed diastereoselective hydroarylation of benzylidene malonic esters

Herein we report that simple Lewis acids catalyze the hydroarylation of benzylidene malonates with phenols. Ultimately, 3,4-disubstituted dihydrocoumarins are obtained via a hydroarylation-lactonization sequence. Moreover, the dihydrocoumarins are formed with a high degree of diastereoselectivity favoring the trans stereoisomer