The present invention relates to processes for the enantio-selective preparation of spyrrolidine derivatives useful in the manufacture of pesticidally active compounds, as well as to intermediates in the processes. The processes include those comprising(a-i) reacting a compound of formula Ia wherein P is alkyl, aryl or heteroaryl, each optionally substituted, wherein the heteroaryl is connected at P via a ring carbon atom; R1 is chlorodifluoromethyl or trifluoromethyl; R2 is aryl or heteroaryl, each optionally substituted; with a source of cyanide in the presence a chiral catalyst to give a compound of formula IIa wherein P, R1 and R2 are as defined for the compound of formula Ia; and (a-ii) oxidizing the compound of formula IIa with a peroxy acid, or peroxide in the presence of an acid to give a compound of formula VI wherein R1 and R2 are as defined for the compound of formula Ia.