(Z)-5-(2-(1H-Indol-3-yl)-2-oxoethylidene)-3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones (7a–w) have been synthesized by the Knoevenagel condensation reaction of 3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones (3a–d) with suitably substituted 2-(1H-indol-3-yl)2-oxoacetaldehydes (6a–g) under microwave conditions. The thioxothiazolidin-4-ones were prepared from the corresponding aryl/alkyl amines (1a–d) and di-(carboxymethyl)-trithiocarbonyl (2). The aldehydes (6a–g) were synthesized from the corresponding acid chlorides (5a–g) using HsnBu3.

3-(6-Phenylimidazo[2,1-b]thiazol-5-yl)quinoxalin-2(1H)-ones (qunoxalinone) (6a–q) have been synthesized by the reaction of ethyl 2-oxo-2-(6-phenylimidazo[2,1-b]thiazol-5-yl)acetates (4a–e) with suitably substituted o-phenylenediamines (5a–f) under microwave heating. The ethyl 2-oxo-2-(6-phenylimidazo[2,1-b]thiazol-5-yl)acetates (4a–e) were prepared by the reaction of 6-phenylimidazo[2,1-b]thiazoles (3a–e) with ethyl chlorooxoacetate in refluxing 1,4-dioxane whereas the thiazoles (3a–e) were synthesized by the reaction of 2-bromo-1-phenylethanones (2a–e) with thiazol-2-amine in refluxing acetone.

N-Phenyl-4-(6-phenylimidazo[2,1-b]thiazol-5-yl)thiazol-2-amines (6a–q) have been synthesized by the Hantzsch thiazole reaction of 2-chloro-1-(6-phenylimidazo[2,1-b]thiazol-5-yl)ethanones (4a–e) with suitably substituted thioureas using microwave heating. The ethanones (4a–e) were prepared by the reaction of 6-phenylimidazo[2,1-b]thiazoles (3a–e) with chloroacetylchloride in refluxing 1,4-dioxane whereas the thiazoles (3a–e) were synthesized by the reaction of 2-bromo-1-phenylethanones (2a–e) with thiazol-2-amine in refluxing acetone.

(5Z,5′Z)-3,3′-(1,4-Phenylenebis(methylene)-bis-(5-arylidene-2-thioxothiazolidin-4-one) derivatives (5a–r) have been synthesized by the condensation reaction of 3,3′-(1,4- or 1,3-phenylenebis(methylene))bis(2-thioxothiazolidin-4-ones) (3a,b) with suitably substituted aldehydes (4a–f) or 2-(1H-indol-3-yl)2-oxoacetaldehydes (8a–c) under microwave conditions. The bis(2-thioxothiazolidin-4-ones) were prepared from the corresponding primary alkyl amines (1a,b) and di-(carboxymethyl)-trithiocarbonyl (2). The 2-(1H-indol-3-yl)-2-oxoacetaldehydes (8a–c) were synthesized from the corresponding acid chlorides (7a–c) using HSnBu3.

(Z)-5-(2-(1H-Indol-3-yl)-2-oxoethylidene)-3-phenyl-2-thioxothiazolidin-4-one (7a–q) derivatives have been synthesized by the condensation reaction of 3-phenyl-2-thioxothiazolidin-4-ones (3a–h) with suitably substituted 2-(1H-indol-3-yl)-2-oxoacetaldehyde (6a–d) under microwave condition. The thioxothiazolidine-4-ones were prepared from the corresponding aromatic amines (1a–e) and di-(carboxymethyl)-trithiocarbonyl (2). The aldehydes (6a–h) were synthesized from the corresponding acid chlorides (5a–d) using HSnBu3.

Several 2-(2-chlorophenyl)-1-phenylethanones and (2-chlorophenyl)(phenyl)methanones were prepared by the Friedel–Crafts acylation reaction of 2-(2-chlorophenyl) acetic acids and 2-chlorocarboxylic acids, respectively, in the presence of cyanuric chloride, pyridine, and AlCl3 or FeCl3 using microwave heating. The yields of the ketones were significantly higher than those obtained using conventional heating. In addition, similar reactions carried out with the less inexpensive and less toxic FeCl3 gave titled ketones in comparable yields. Interestingly, the FeCl3 catalyzed reactions gave pure ketones (no chromatographic purification required), whereas the AlCl3 catalyzed reaction gave impure product that required chromatographic purification.