New heterocyclic compounds

摘要

A compound of the formula : wherein R<1> is halogen, R<2> and R<3> are each hydrogen, lower alkyl, halo(lower)alkyl or acyl, R<4> is aryl having suitable substituent(s), or a heterocyclic group optionally having suitable substituent(s), Q is O or N-R<1><1>, in which R<1><1> is hydrogen or acyl, and A is lower alkylene, and pharmaceutically acceptable salts thereof, processes for their preparation and pharmaceutical compositions comprising them as an active ingredient.