. "The second aspect of the present invention is directed to a process for producing a compound of the formula (1) or a pharmaceutically acceptable acid addition salt thereof which comprises reacting a compound represented by the formula (2): ##STR4## wherein R1, R2, R3, R4, Y1, Y2, Y3, Y4, Y5, Y6, Y7 and Z are as defined above, and J is a leaving group replaceable by a nucleophilic reagent, with gua" . . . .