The first example of chiral induction using homochiral boronic esters in the Petasis reaction

The present study demonstrates the first enantioselective version of the Petasis reaction (boronic Mannich reaction), using glyoxylic acid, morpholine and a homochiral boronic ester as the chiral auxiliary. Chiral boronic esters are readily prepared by condensation of vinylboronic acids and chiral 1,2-diols. In the resulting Petasis reaction, 2-morpholin-1-yl-4-phenylbut-3-enoic acids are formed in high yields and moderate enantioselectivity.