A series of N-(3-(substituted-alkyl- or halophenyl)-4-methylthiazol-2(3H)-ylidene)-substituted alkyl- or halo-benzamides 21 - 40 were prepared by base-catalyzed cyclization of the corresponding 1-(substituted-alkyl- or halo-benzoyl)-3-(substituted-halophenyl)thioureas 1 - 20. Substituted pyrazolo[ 4,3-d]thiazol-5(6aH)-ylidene)benzamides 45a - d were synthesized by cycloaddition of compound 45 with the reactive cumulene intermediates 42a - d. All compounds were evaluated for their antiviral activity against the replication of HIV