A Comparative Study on the Synthesis of 3'-Aryl-3-methyl/2, 3-Dimethylspiro[6,7,8,9-tetrahydro-5H-benzo[a]cyclohepten-5, 2'-(Tetrahydro[1,3]thiazolane)]-4'-ones Using Microwave Irradiation and ConventionalMethods. -The one-pot synthesis of new spirothiazolidine derivatives (IV) (8 examples) by consecutive condensation of cycloheptenones (I) with aromatic amines (II) and mercaptoacetic acid under both microwave irradiation and conventional, thermal conditions is described. Both methods give moderate yields, but reaction times are reduced from several hours to a few minutes using microwave irradiation. Some of the spiro-compounds obtained show good antimicrobial activity. -(VENKATESWARLU*, P.; VASIREDDY, N. R.; J.