Boron-mediated aldol reactions of ethyl α-(N,N)-dibenzylamino ketones: control of enolisation geometry and aldehyde π-facial selectivity

The boron-mediated aldol reactions of a range of chiral α-(N,N)-dibenzylamino ketones with aldehydes can be controlled to provide stereodefined adducts. Complementary induction can be achieved with cHex2BCl/Me2NEt leading to preferential formation of the 1,2-anti-2,4-syn adducts, while Bu2BOTf/iPr2NEt provides 1,2-syn-2,4-anti adducts.