Tetrahedron letters

A convenient one-pot synthesis of 4-amino-3-arylpyrazoles from α-phthaloylaminoacetophenones

C Chen, K Wilcoxen, JR McCarthy

Index: Chen, Chen; Wilcoxen, Keith; McCarthy, James R. Tetrahedron Letters, 1998 , vol. 39, # 45 p. 8229 - 8232

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Citation Number: 17

Abstract

Condensation of α-phthaloylaminoacetophenones 1a-c with N, N-dimethylformamide dimethyl acetal afforded the novel enamines 3a-c. Cyclization of 3 with hydrazine, alkylhydrazine or phenylhydrazine salts (4a-d) gave 4-phthaloylamino-3-arylpyrazoles 7–9 in high yields. Deprotection of 7–9 was accomplished with hydrazine to provide 4-amino-3- arylpyrazoles 5 in good yields.