"In another process for the preparation of intermediates of formula (3), an alkene of formula (4): ##STR5## may be coupled in a Heck reaction with an organopalladium compound derived from a compound R5 Hal where Hal is a halogen atom such as a bromine atom! and a palladium salt such as palladium acetate in the presence of a phosphine such as tri-o-tolyl phosphine and a base such as triethylamine at" . . . .