Novel heterocycles containing the pyrazole unit

Abstract

New condensed pyrazolo[1,5-e][1,3,5]benzoxadiazocine and bridged 5,11-methano-[1,2,4]triazolo[1,2-c][1,3,4]benzoxadiazepine heterocyclic ring systems were prepared by cyclizations of 4,5-dihydro-3-methyl-5-(2-hydroxyphenyl)-1H-pyrazole-1-carboximidamide with C₁ reagents (triethylorthoformate and 1,1′-carbonyldiimidazole). In contrast, cyclocondensations with C₂ and C₃ reactants occur exclusively at the amidine moiety yielding substituted pyrano[2,3-d]pyrimidine, pyrimidine, and imidazole derivatives.