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Synthesis of 1,2,4-Triazolo[4,3-a]pyrimidine Derivatives by Cyclocondensation of a 2-Thioxopyrimidin-4(3H)-one with Hydrazonoyl Halides


Elwan, Nehal M; Awad, Enas M; Hassaneen, Hamdi M; Linden, Anthony; Heimgartner, Heinz (2003). Synthesis of 1,2,4-Triazolo[4,3-a]pyrimidine Derivatives by Cyclocondensation of a 2-Thioxopyrimidin-4(3H)-one with Hydrazonoyl Halides. Helvetica Chimica Acta, 86:739-749.

Abstract

The reaction of 1,2-dihydro-6-(phenylamino)-2-thioxopyrimidin-4(3H)one (16) with N-arylhydrazonoyl halides 15 in CHCl3 in the presence of Et3N under reflux afforded the corresponding 1,2,4-triazolo[4,3-a]pyrimidin-5-ones of type 20 in good yields (Scheme 3). The structure of one of the derivatives, 20d, has been established by X-ray crystallography. Conceivable reaction mechanisms are discussed in Schemes 3 and 4. The products of type 20 easily undergo reactions with electrophiles such as benzenediazonium chloride, chloroacetyl chloride, and NaNO2 in AcOH to give 6-phenylazo, 6-chloroacetyl, and 6-nitroso derivatives 21, 23, and 25, respectively (Scheme 5).

Abstract

The reaction of 1,2-dihydro-6-(phenylamino)-2-thioxopyrimidin-4(3H)one (16) with N-arylhydrazonoyl halides 15 in CHCl3 in the presence of Et3N under reflux afforded the corresponding 1,2,4-triazolo[4,3-a]pyrimidin-5-ones of type 20 in good yields (Scheme 3). The structure of one of the derivatives, 20d, has been established by X-ray crystallography. Conceivable reaction mechanisms are discussed in Schemes 3 and 4. The products of type 20 easily undergo reactions with electrophiles such as benzenediazonium chloride, chloroacetyl chloride, and NaNO2 in AcOH to give 6-phenylazo, 6-chloroacetyl, and 6-nitroso derivatives 21, 23, and 25, respectively (Scheme 5).

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2003
Deposited On:25 Sep 2013 14:05
Last Modified:05 Apr 2016 17:00
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Swiss Federal Government (National Scholarship for Foreign Students)
Publisher DOI:https://doi.org/10.1002/hlca.200390073

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