Chemoenzymic synthesis and fungicidal activity of the four pure stereoisomers of a new morpholine derivative

Four optically pure stereoisomers of 2,6-dimethyl-4-[2-methyl-3-[3-(cyclopropylmethoxy)phenyl]propyl]-morpholine (1), a new broad-spectrum morpholine fungicide, were prepared starting from the chiral precursor 2-methyl-3-[3-(benzyloxy)phenyl]-1-propanol (2). Optically active 2 was obtained by lipase-catalyzed kinetic resolution of (R, S)-2 and by stereoselective bakers' yeast reduction of 2-methyl-3-[3-(benzoyloxy)phenyl]propenal (4). The biological activity of the pure stereoisomers has been evaluated in vitro against a variety of fungi and in vivo against Erysiphe graminis on wheat and Helminthosporium teres on barley