| abstract |
PURPOSE: To provide a chiral catalyst by which high chirality can be obtained in the asymmetrical reduction of ketones to secondary alcohols by reacting an N-carboxy anhydride with an aryl metal, and then reacting the same with boroxine. n CONSTITUTION: A compound of formula I (n is 1 or 2; R 1 and R 2 are H, a 1-3C alkyl, or R 1 and R 2 form together a benzo group with C bonded thereto or a double bond), is reacted with a magnesium phenyl halide reagent in an ether solvent at -25 through +10°C, to prepare diarylmethanol of formula II [Ar is 2-naphthyl, phenyl or phenyl substituted with one or more halo, 1-4C alkyl, CF 3 , or 1-4C alkoxy at 3 position and/or 4 position thereof]. The resulting compound is reacted with substituted boroxine of formula III [R is a 1-4C alkyl, or phenyl optionally having substituent (halo, alkyl, CF 3 or alkoxy)] in an organic solvent at 80-150°C, to prepare an oxazoborolidine catalyst of general formula IV. n COPYRIGHT: (C)1992,JPO |