Studies on 4-Thiazolidinones: Scope of the Reactions of 3-Aryl-2-thioxo-1,3-thiazolidin-4-ones with Cyanide and Cyanate Ions (original) (raw)

Treatment of 3-aryl-2-thioxo-1,3-thiazolidin-4-ones 1 with CN À and NCO À effected the ring cleavage providing [(cyanocarbonothioyl)amino]benzenes 4 and arylisothiocyanates 5, respectively. Similar treatment of 5-(2-aryl-2-oxoethyl) derivatives 2 afforded 2,4-bis(2-aryl-2-oxoethylidene)cyclobutane-1,3-diones 6 along with each of the preceding products. Treatment of the respective (E,Z)-5-(2-aryl-2oxoethylidene) analogues 3b and 3c with CN À gave 4b and 4c and 2-(arylcarbonyl)-2-methoxy-4oxopentanedinitriles 7b and 7c, in addition to 3,6-bis[2-(4-chlorophenyl)-1-methoxy-2-oxoethylidene]-1,4-dithiane-2,5-dione 8c, which has been generated from 3c. Reactions of 3c or 3d with NCO À provided 5c or 5d, together with 8c or 8d as pure isomers. In the formation of the MeO products 7 and 8, the solvent (MeOH) has participated. Structures of these products are based on microanalytical and spectroscopic data. Rationalizations for the above transformations are given.