| abstract |
The present invention provides a stereoselective process for the preparation of compounds of formula (I) wherein P is phenyl, naphthyl, a 6-membered heteroaryl group containing one or two nitrogen atoms as ring atoms, or a 10-membered bicyclic heteroaryl group containing one or two nitrogen atoms as ring atoms, and wherein the benzene Ryl, naphthyl, and heteroaryl groups are optionally substituted; R is chlorodifluoromethyl or trifluoromethyl; R is optionally substituted aryl or optionally substituted heteroaryl ; n is 0 or 1; including the following methods, the method comprising: (ai) making a compound of formula II wherein P, R and R are as defined for the compound of formula I; reacting with nitromethane in the presence of a chiral catalyst to give a compound of formula III wherein P, R and R are as defined for the compound of formula I; and (a-ii) reductively cyclizing the compound of formula III to give the compound of formula I. The present invention also provides intermediates useful in the process of synthesizing compounds of formula (I). |