. "The process comprises reacting a carboxylic acid reactive derivative of the formula (2): ##STR8## wherein R1,R2, R3, R4, Y1, Y2, Y3, Y4, Y5, Y6, Y7 and Z are as defined above, and J is a leaving group easily replaceable by a nucleophilic reagent, with guanidine to form the guanidinocarbonyl group (--C(???O)N???C(NH2)2 group shown in the formula (1) and, if necessary, converting the reaction produc" . . . .