The present disclosure relates to compounds of the formula wherein R2 and A are certain substituents, Y is an ester group, a nitrile group or an amido group and Z is O, S or N+R2, and which compounds are, for example, useful as intermediates for pyrazole fungicides. The compounds of the present disclosure can be prepared by the reaction of a compound of formula R2—C(O)—CH2Y, with an orthoformate HC—(OR3)3 in the presence of a base, especially in the presence of an amine, e.g. triethylamine.