| abstract |
Procedure for preparing a compound of formula 5 or 5 *, or a mixture thereof: ** (See formula) ** The method comprising: (a) reacting a compound of formula 6: ** (See formula) ** with nitromethane in the presence of a chiral catalyst of formula 3 or 3 *: ** (See formula) ** in which R4 and R5 are H; to provide a compound of formula 7 or 7 *, or a mixture thereof; and ** (See formula) ** (b) converting a compound of formula 7 or 7 *, or a mixture thereof, to a compound of formula 5 or 5 *, or a mixture thereof; wherein each R3 is independently halo, -O (C = O) -alkyl having 1 to 12 carbon atoms, -O (C = O) -O-alkyl having 1 to 12 carbon atoms, or - O (SO2) -alkyl having 1 to 12 carbon atoms. |