Biocatalytic enantioselective approach to 3-aryl-2-nitropropanols: Synthesis of enantioenriched (R)-5-methoxy-3-aminochroman, a key precursor to the antidepressant drug Robalzotan

The results of our studies on the biocatalytic enantioselective synthesis of different 3-aryl-2-nitropropanols are presented. These compounds could be obtained in moderate to good ee both by baker's yeast mediated reduction of (E)-2-nitro-3-arylprop-2-en-1-ol precursors and by lipase kinetic resolution of racemic 3-aryl-2-nitropropanols. The synthesis of enantioenriched (R)-5-methoxy-3-aminochroman is also achieved. This important moiety is present in different molecules active toward the central nervous system and is also the precursor for the synthesis of Robalzotan (NAD299), a potent 5-HT1A antagonist.