Process for the preparation of intermediates useful in the preparation of pyranyl cyanoguanidine derivatives

摘要

A process for preparing compounds of the formula <IMAGE> I where a, b, c, R1, R2, and R3 are as defined herein including the step of alkylating a phenol of formula <IMAGE> II with an acetylene of formula <IMAGE> III where X is chlorine; bromine; -OC(O)-R5, where R5 is alkyl, aryl or substituted aryl; or -OCO2R6, where R6 is alkyl or <IMAGE> in the presence of a catalytic amount of a cuprous or cupric salt. The compounds of formula I are intermediates useful in the preparation of pyranyl cyanoguanidine derivatives.