Conversion of 3-amino-4-arylamino-1H-isochromen-1-ones to 1-arylisochromeno[3,4-d][1,2,3]triazol-5(1H)-ones: synthesis, spectroscopic characterization and the structures of four products and one ring-opened derivative

Abstract

An efficient synthesis of 1-arylisochromeno[3,4-d][1,2,3]triazol-5(1H)-ones, involving the diazotization of 3-amino-4-arylamino-1H-isochromen-1-ones in weakly acidic solution, has been developed and the spectroscopic characterization and crystal structures of four examples are reported. The molecules of 1-phenylisochromeno[3,4-d][1,2,3]triazol-5(1H)-one, C 15 H 9 N 3 O 2 , (I), are linked into sheets by a combination of C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, while the structures of 1-, each contain just one hydrogen bond which links the molecules into simple chains, which are further linked into sheets by -stacking interactions in (II) but not in (III). In the structure of 1-(4chlorophenyl)isochromeno [3,4-d][1,2,3]triazol-5(1H)-one, (IV), isomeric with (III), a combination of C-HÁ Á ÁO and C-HÁ Á Á(arene) hydrogen bonds links the molecules into sheets. When compound (II) was exposed to a strong acid in methanol, quantitative conversion occurred to give the ring-opened transesterification product methyl 2-[4-hydroxy-1-(2-methylphenyl)-1H-1,2,3-triazol-5-yl]benzoate, C 17 H 15 N 3 O 3 , (V), where the molecules are linked by paired O-HÁ Á ÁO hydrogen bonds to form centrosymmetric dimers.