Selective reduction of -dimethoxyphenyl)-2(2-methoxyphenoxy)-propan-1-
one (1) to give the title compound was investigate using various reduc
ing agents. Reduction of the ketone with either R-(+)- or S-(-)-2-meth
yl-CBS-oxazaborolidine/BH3 gave about 10:90 erythro:threo. The product
was further purified to about 99% using low-pressure silica gel colum
n chromatography. A mechanism to give the two threo enantiomers is pro
posed.