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 IIwherein 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 IIIwherein 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.The invention also provides intermediates useful for processes for the synthesis of compounds of formula (I).本發明提供一種用於製備式(I)化合物之立體選擇性方法其中P係苯基、萘基、包含一或二個氮原子作為環員之6-員雜芳基基團、或包含一或二個氮原子作為環員之10-員二環雜芳基基團、以及其中苯基、萘基以及雜芳基基團係視需要經取代;R1係氯二氟甲基或三氟甲基;R2係視需要經取代的芳基或視需要經取代的雜芳基;n係0或1;包括包含以下之方法(a-i)使式II化合物其中P、R1以及R2係如式I化合物所定義;與硝基甲烷於對掌性催化劑存在下反應而得到式III化合物其中P、R1以及R2係如式I化合物所定義;以及(a-ii)還原地環化式III化合物而得到式I化合物。本發明亦提供用於合成式(I)化合物之方法的中間體。
