7_H thieno[2,3-a]quinolizines, useful as alpha 2-andrenoceptor antagonist

The invention concerns thienoquinolizines of general formula (I) (I) and their pharmaceutically acceptable acid addition salts. In the formula R1 is hydrogen or lower alkyl and R2 is lower alkyl, halo(lower)alkyl, -A-NR3R4 [where A represents a direct bond between the S and N atoms or a lower alkylene group having 1 to 3 carbon atoms in the chain between the S and N atoms and R3 and R4 each independently represent hydrogen, lower alkyl, aryl or aryl(lower)alkyl or together with the nitrogen atom to which they are attached represent a five or six membered heterocyclic ring], aryl or a heterocyclic radical or R1 is -A1NR5.SO2R6 [where A1 is a lower alkylene group having 1 to 3 carbon atoms in the chain between the two N atoms, R5 is hydrogen or lower alkyl and R6 is lower alkyl, halo(lower)alkyl or aryl] and R2 is lower alkyl, halo(lower)alkyl or aryl. The compounds possess alpha 2-adrenoceptor antagonistic activity in warm blooded animals.