Synthesis of 6-Aryl-6H-Chromeno[4’,3’:4,5][1,3]Thiazolo[3,2-A]Benzimidazoles from 2-Aryl-3-Nitro-2H-Chromenes and 1H-Benzimidazole-2-Thiol

Synthesis of spiro[benzo[4,5]imidazo[2,1-b][1,3]thiazole-2,3-thiolane]s via sulfa-Michael/aldol cascade reactions

The sulfa-Michael/aldol cascade reaction of ( Z)-2-arylmethylidene-benzo[4,5]imidazo[2,1- b]thiazol-3(2H)-ones and 1,4-dithiane-2,5-diol afforded novel 2-aryl-4-hydroxy-spiro[benzo[4,5]imidazo[2,1- b][1,3]thiazole-2,3-thiolan]-3-ones in moderate yields. The structures of all the products were characterized thoroughly by nuclear magnetic resonance, infrared and high-resolution mass spectrometry together with X-ray crystallographic analysis.

Synthesis of 4-Aryl-3,4,5,6-Tetrahydropyrimido[5,4-g]Indolizine-2(1H)-Thione

A number of 4-aryl-3,4,5,6-tetrahydropyrimido[5,4-g]indolizine-2(1H)-thiones were synthesised by the reaction of (7E)-7-arylidene-6,7-dihydroindolizin-8(5H)-one and thiourea in the presence of potassium hydroxide in moderate yields. The structures of all the products were characterised thoroughly by NMR, IR and HRMS together with X-ray crystallographic analysis.

Synthesis of spiro[cyclopent-2/3-ene-1,2′-[1,3]thiazolo[3,2-a] pyrimidine] derivatives via 1,3-dipolar cycloaddition reaction of ethyl buta-2,3-dienoate

The 1,3-dipolar cycloaddition reaction of ethyl (2Z)-5-aryl-2-(2-methoxy-2-oxoethylidene)-7-methyl-2,3-dihydro-5H-thiazolo[3,2-a] pyrimidine-6-carboxylate and ethyl buta-2,3-dienoate catalysed by triphenylphosphine afforded novel spiro[cyclopent-2-ene-1,2′-[1,3] thiazolo[3,2-a]pyrimidine] and spiro[cyclopent-3-ene-1,2′-[1,3]thiazolo[3,2-a]pyrimidine] derivatives in moderate yields. The structures of all the products were characterised thoroughly by NMR, IR and HRMS together with X-ray crystallographic analysis.

Synthesis of Dispiro[Indeno[1,2-b]Quinoxaline-11,3′-Pyrrolizine-2′,2″-[1,3] Thiazolo[3,2-a]Pyrimidine Via Cycloaddition Reactions

The 1,3-dipolar cycloaddition reaction of ethyl 5-aryl-2-(2-methoxy-2-oxoethylidene)-7-methyl-3-oxo-2,3-dihydro-5 H-[1,3]thiazolo[3,2- a] pyrimidine-6-carboxylate and azomethine ylide, which was generated in situ by the reaction of 11 H-indeno[1,2- b]quinoxalin-11-one and L-proline, afforded novel 6″ethyl 1′-methyl 5″aryl-7″methyl-3″oxo-5’,6’,7’,7a′-tetrahydro-1' H,3″ H,5″ H-dispiro[indeno[1,2- b]quinoxaline-11, 3 ‘-pyrrolizine-2’,2″-[1,3]thiazolo[3,2- a]pyrimidine-1’,6″-dicarboxylates in good yields. The structures of all the products were characterised thoroughly by NMR, IR and HRMS together with X-ray crystallographic analysis.