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Molecules 2011, 16(5), 3723-3739; doi:10.3390/molecules16053723
Article

Acylation of Heteroaromatic Amines: Facile and Efficient Synthesis of a New Class of 1,2,3-Triazolo[4,5-b]pyridine and Pyrazolo[4,3-b]pyridine Derivatives

1,2, 1,* , 1 and 1
Received: 14 March 2011 / Revised: 21 April 2011 / Accepted: 26 April 2011 / Published: 4 May 2011
(This article belongs to the Section Organic Synthesis)
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Abstract

1,2,3-Triazolo[4,5-b]pyridines and pyrazolo[4,3-b]pyridines can be readily prepared via cyanoacetylation reactions of 5-amino-1,2,3-triazoles 1a,b and 4-amino- pyrazole 2 followed by subsequent cyclization of the formed cyanoacetamides. Reactions of amines 1a,b with a mixture of p-nitrophenylacetic acid and acetic anhydride under microwave irradiation conditions afforded the corresponding amides 15a,b that underwent cyclization to form 1,2,3-triazolo[4,5-b]pyridines 16a,b upon heating in DMF solutions containing sodium acetate. Reactions of 1a,b with active methylene compounds, including 17a-c, in the presence of zeolites as catalyst also afforded 1,2,3-triazolo[4,5-b]pyridine derivatives 20a-f via the intermediacy of triazole derivatives 19 and not 18.
Keywords: cyanoacetic acid; cyanoacetamides; triazolo[4,5-b]pyridine; pyrazolo[4,3-b]- pyridine; p-nitrophenylacetic acid; zeolite cyanoacetic acid; cyanoacetamides; triazolo[4,5-b]pyridine; pyrazolo[4,3-b]- pyridine; p-nitrophenylacetic acid; zeolite
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Ibrahim, H.M.; Behbehani, H.; Makhseed, S.; Elnagdi, M.H. Acylation of Heteroaromatic Amines: Facile and Efficient Synthesis of a New Class of 1,2,3-Triazolo[4,5-b]pyridine and Pyrazolo[4,3-b]pyridine Derivatives. Molecules 2011, 16, 3723-3739.

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