PURPOSE: Pyrrole derivatives of formula I (R 1 , R 2 are 1 W 3C alkyl; R 3 is H, cycloalkyl, 2 W 4C alkenyl, 1 W 6C alkyl substituted with saturated heterocyclic group, 1 W 6C alkyl substituted with phenyl which may have alkoxy group as a substituent). n COPYRIGHT: (C)1979,JPO&Japio