Bronsted acid-catalyzed insertion of aryldiazoacetates to [sp.sup.2] carbon-CHO bond: facile construction of chiral all-carbon quaternary center

The triflic acid-catalyzed formal C-C bond insertion of aryldiazoacetates to aldehydes is used a means for constructing an all-carbon quaternary center. The introduction of the phenylmenthyl moiety as chiral auxiliary has allowed the facile access to a variety of optically active [alpha],[alpha]-disubstituted-[alpha]-formyl esters.