Convenient synthesis of fused heterocycles from α-ketohydroximoyl chlorides and heterocyclic amines |
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| Authors: | Cyril PÁrkÁnyi Abdou O Abdelhamid John C S Cheng Ahmad S Shawali |
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| Institution: | 1. Department of Chemistry, The University of Texas at El Paso, El Paso, Texas 79968–0513;2. Department of Chemistry, Faculty of Science, King Abdul Aziz University, P. O. Box 9028, Jeddah 21413, Saudi Arabia |
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| Abstract: | Nitroso derivatives of imidazo1,2-a]pyridine ( 11, 13, 14 ), imidazo1,2-a]pyrimidine ( 15 ), imidazo1,2-a]pyrazine ( 16 ), imidazo1,2-b]pyrazole ( 17 ), and imidazo1,2-b]-1,2,4-triazole ( 19 ) were obtained in good yields from α-ketohydroximoyl chlorides 3 and 2-aminopyridines ( 4–6 ), 2-aminopyrimidine ( 7 ), 2-aminopyrazine ( 8 ), 5-amino-3-phenylpyrazole ( 9 ), and 3-amino-2H-1,2,4-triazole ( 10 ), respectively. Under different conditions, the reaction of 3 with 3-amino-2H-1,2,4-triazole ( 10 ) and 2-aminopyrazine ( 8 ) afforded the noncyclized substitution products 18 and 22 , respectively. The structures of the products were assigned and confirmed on the basis of their elemental analyses, spectral data, and alternate synthesis wherever possible. |
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