Reaction of 5-arylmethylene-2-thioxo-4-thiazolidinones with some phosphonium ylides. Synthesis of thiazolidino[4,5- x]-fused compounds

Abstract

The reactions of the entitled compounds ( 4a) and ( 4b) with some phosphonium ylides ( 5a–d) have been studied in considerable detail. By applying the Wittig reagents ( 5a,b) on the thiazolidinones ( 4a,b) in refluxing ethyl acetate and in the presence of triethylamine, conjugated dihydro-furo[2,3- d]thiazol-2( 3H)-ones ( 7a–d) were obtained while carrying out the reaction in refluxing toluene and also in the presence of triethylamine led to the formation of the pyrone derivatives ( 8). Reaction of 4a,b with oxoylide ( 5c), afforded the pyranderivatives ( 10). On the contrary, the reaction of 4a,b with 5d underwent 1,2-addition reaction to yield the new ylides ( 12a,b) as a sole reaction product. Except the last reaction of 4a,b with 5d, other reactions afforded, in each instance, the olefinated products ( 9a–d) and ( 11a,b) in 11–18% yield.