A highly enantioselective conjugate reduction of 3-arylinden-1-ones using bakers' yeast for the preparation of (S)-3-arylindan-1-ones

[GRAPHICS] The bakers' yeast reduction of 3-(1,3-benzadioxol-5-yl)-6-propoxy-1H-inden- 1-one 4 has been shown to give (S)-3-(1,3-benzodioxol-5-yl)-2,3-dihydro-6-p ropoxy-1H-indan-1-one 6 in 65% yield with high enantioselectivity (>99.0% e e), a key intermediate for the synthesis of the endothelin receptor antagon ist SE 217242, In addition, the substituted 3-arylinden-1-ones 10a-e gave e qually high enantioselectivity for the 3-arylindan-1-one products 13a-e, Me chanistic studies of the reaction indicate the operative pathway to be an a symmetric conjugate reduction, wherein the hydride transfer from NAD(P)H oc curs from the Re-face of the indenone substrate.