A Facile One-Step Synthesis of New Types of 8-Thiazolyl and 8-Thiadiazinyl Coumarins

Abstract

N-[4-(7-Methoxy-4-methyl-2-oxo-2H-chromen-8-yl)-thiazol-2-yl]-guanidine ( 2 ) has been prepared by the condensation of 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin ( 1 ) with guanylthiourea. 4-Methyl-7-methoxy-8-[2-(N′-(1-phenyl-ethylideneisopropylidene)-hydrazino]-thiazol-4-yl]chromen-2-ones ( 3 , 4 , and 5 ) have been prepared by reaction of 4-methyl-7-methoxy-8-(2-bromoacetyl) coumarin ( 1 ) and thiosemicarbazide in presence of acetophenone or acetone without any solvent. The formation of these compounds was further confirmed by the condensation of acetophenone/acetone thiosemicarbazones with 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin ( 1 ) in anhydrous ethanol in a two-step process. Similarly 8-[2-[N′-(benzylidene)hydrazine]-thiazol-4-yl]-7-methoxy-4-methyl-chromen-2-ones ( 6 , 7 , and 8 ) have been prepared by the condensation of 4-methyl-7-methoxy-8-(2-bromoacetyl)chromen-2-one with thiosemicarbazide and various aromatic aldehydes in a single step without any solvent. The formation of these compounds was further confirmed by the condensation of appropriately substituted benzaldehyde thiosemicarbazones with 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin in anhydrous ethanol. 4-Methyl-7-methoxy-8-(2-bromoacetyl) chromen-2-one (1) upon condensation with 3,5-dimercapto-4-amino-s-triazole in anhydrous ethanol resulted in the formation of 8-(3-mercapto-3H-[1,2,4]triazolo[3,4-b]thiadiazin-6-yl)-7-methoxy-4-methyl chromen-2-one (9). This compound ( 9 ) on reaction with various alkyl and phenacyl halides in anhydrous ethanol gave corresponding 4-methyl-7-methoxy-8-[3-(2-oxo-substituted sulphanyl)-7H-[1,2,4]triazolo[3,4-b]thiadiazin-6-yl]chromen-2-ones ( 10 to 18 ). The structures of newly prepared compounds have been confirmed from analytical and spectral data.