Abstract: The present invention provides stereoselective processes 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 members, or a 10-membered bicyclic heteroaryl group containing one or two nitrogen atoms as ring members, and wherein the phenyl, naphthyl and heteroaryl groups are optionally substituted; R1 is chlorodifluoromethyl or trifluoromethyl; R2 is optionally substituted aryl or optionally substituted heteroaryl; n is 0 or 1; including the process comprising (a-i) reacting a compound of formula II wherein P, R1 and R2 are as defined for the compound of formula I; with nitromethane in the presence a chiral catalyst to give a compound of formula III Wherein P, R1 and R2 are as defined for the compound of formula I; and (a-ii) reductively cyclising the compound of formula III to give the compound of formula I.