Taizo Hatta

Ring closure reactions of adducts of methacryloyl isocyanate to arylhydrazines and their related compounds

Methacryloyl isocyanate (MAI) reacted with arylhydrazines (1) to give semicarbazides (2) in good yields. Treatment of (2) with aqueous potassium hydroxide gave the corresponding 1-aryl-3-hydroxy- 1,2,4-triazoles (3), whereas thermal ring closure of (2) afforded isomeric 2,3-dihydro-2-aryl-1,2,4-triazole-3(1H)-ones (4). MAI reacted with benzamidine to give directly 1,3,5-triazine-2(1H)-one (10) by the loss of water. On the other hand, the reaction of MAI with 1,3-diphenyl- guanidine afforded the 1:1 adduct (11), which on thermal decomposition gave the perhydropyrimidin-6(1H)-one (12) and perhydro-1,3,5-triazine- 2,6-dione (13). The pathways for the formation of (4), (12) and (13) are also described

Tautomerism (hydroxyazo versus ketohydrazone form) of [2.2.2] cyclophane-1,2-dione monoarylhydrazones: an 1H-NMR study

Abstract Hydroxyazo-ketohydrazone tautomerism of arylhydrazones of para-para-para-, para-meta-para-, and para-ortho-para-[2.2.2]cyclophane-1,2-dione 1a, 1b and 1c was studied by means of 1H-NMR spectroscopy. Except for the phenylhydrazones 4ba and 4ca of 1b and 1c, which exist as the ketohydrazone 4-H, the azo tautomer 4-A is predominant in solution, and is more favored in chloroform and benzene than in acetonitrile. A good correlation was found between the strain of the cyclophane ring and the δ-value of OH proton in 4-H.

Sulphur nitride in organic chemistry. Part 17. Preparation of 1,8-diaminocarbazole

Tetrasuiphur tetranitride (1) reacted with 5,5′-di-t-butylbiphenyl-2,2′-diol (3a–d) to give 4-(2-hydroxyphenyl)-2,1,3-benzothiadiazole (4a) and (4c), bi-2,1,3-benzothiadiazol-4-yl (5), and benzofurano[3,2-e]-2,1,3-benzothiadiazole (6), the yields of which were dependent upon the ortho substituent of (3) and an equimolar ratio of (1) : (3). Reduction of compound (5) with SnCl2in acetic acid-concentrated hydrochloric acid gave the imidazolyl-thiazole (11), while reduction with Sn in concentrated hydrochloric acid gave tetra-aminobiphenyl (9), which was diazotised to give the bitriazolyl (12). Compound (9) when heated in phosphoric acid give 1,8-diaminocarbazole (2)[27% yield from the dibromobiphenyldiol (3c)].