Please use this identifier to cite or link to this item: https://doi.org/10.1039/c2ob25195g
Title: Regioselective synthesis of pyrimido[1,2-a][1,3,5]triazin-6-ones via reaction of 1-(6-oxo-1,6-dihydropyrimidin-2-yl)guanidines with triethylorthoacetate: Observation of an unexpected rearrangement
Authors: Sachdeva, N.
Dolzhenko, A.V.
Keung Chui, W. 
Issue Date: 21-Jun-2012
Citation: Sachdeva, N., Dolzhenko, A.V., Keung Chui, W. (2012-06-21). Regioselective synthesis of pyrimido[1,2-a][1,3,5]triazin-6-ones via reaction of 1-(6-oxo-1,6-dihydropyrimidin-2-yl)guanidines with triethylorthoacetate: Observation of an unexpected rearrangement. Organic and Biomolecular Chemistry 10 (23) : 4586-4596. ScholarBank@NUS Repository. https://doi.org/10.1039/c2ob25195g
Abstract: A novel thermal rearrangement, involving pyrimidine ring opening and subsequent ring closure leading to recyclization of the system, was identified in the reaction of (6-oxo-1,6-dihydropyrimidin-2-yl)guanidines 3 (where NR 1R 2 = NH 2, NH alkyl, NH aralkyl, NHCH 2Ph(R)) with triethyl orthoacetate, affording 4-substituted-2-methyl- 6H-pyrimido[1,2-a][1,3,5]triazin-6-ones 6 and their ring opened products. However, no such rearrangement was observed with (6-oxo-1,6-dihydropyrimidin-2- yl)guanidines 3 bearing a tertiary amino or anilino substituent (i.e. where NR 1R 2 = N(CH 3) 2, indoline, morpholino, NHAr). As expected, 2-substituted-4-methyl-6H-pyrimido[1,2-a][1,3,5] triazin-6-ones 4 were obtained as the final products. Experimental structural determination and theoretical studies were carried out to get an understanding of the observed thermal rearrangement. In addition, an attempt to obtain similar pyrimido[1,2-a][1,3,5]triazin-6-ones using N,N-dimethylacetamide dimethyl acetal (DMA-DMA) as one carbon inserting synthon had furnished triazine ring annulated product 14 bearing N,N-dimethyl enamino substituent at position 4 as a result of further reaction with a second molecule of DMA-DMA. © 2012 The Royal Society of Chemistry.
Source Title: Organic and Biomolecular Chemistry
URI: http://scholarbank.nus.edu.sg/handle/10635/106295
ISSN: 14770520
DOI: 10.1039/c2ob25195g
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