SYNTHESIS AND REACTIVITY OF 2-[1-(5-BROMOBENZOFURAN-2-YL)-ETHYLIDENE]MALONONITRILE IN SYNTHESIS OF HETEROCYCLIC SYSTEMS;A CONVENIENT ROUTE FOR SYNTHESIS OF SOME PYRAZOLE, THIOPHENE, THIENOPYRIMIDINE, ISOBENZOFURAN AND BENZENE DERIVATIVES INCORPORATING BENZOFURAN MOIETY