Asymmetric organocatalytic reactions of o-hydroxycinnamaldehydes with organoboronic acids: a facile enantioselective access to chromanes and dihydrobenzopyranes

Catalytic asymmetric 1,4-addition reactions of organoboronic acids to o-hydroxycinnamaldehydes, which afford chromanes and dihydrobenzopyranes, have been established using an organocatalyst derived from imidazolidinone. The chromanes have been obtained in high chemical yields and enantioselectivities and can be readily used to obtain a variety of chromane derivatives through subsequent transformations.