Asymmetric Reduction of Aromatic Ketone in a Continuous Flow System

When THF–borane (1/1) and aromatic ketone were supplied continuously to the column containing polymer-supported (S)-(−)-2-amino-3-(p-hydroxyphenyl)-1,1-diphenyl-1-propanol, the chiral product, secondary benzylic alcohol, could be obtained successfully (>90% ee). Large quantities of highly optically pure alcohol could be produced by the continuous flow system by the use of only a small amount of polymeric auxiliary.