An Efficient Synthesis of 7,8‐Dihydropyrimido[5,4‐d]pyrimidines.

Abstract

Fused pyrimidine derivatives R 0515An Efficient Synthesis of 7,8-Dihydropyrimido[5,4-d]pyrimidines. -Two types of fused pyrimidines are formed by the reaction of cyanopurines (I) with excess ammonia or primary amines. The major pathway involves nucleophilic attack of the amine on C-8 of the purine ring followed by ring-opening of the imidazole and ring-closure on the cyano group in the C-6 purine position. In the case of ammonia, the stable amino tautomers (II) are isolated instead of iminopyrimidines. This type of compound is also formed by the reaction of hydrazine (III) with purine (Ic). -(CARVALHO, M. A.; ESPERANCA, S.; ESTEVES, T.; PROENCA*, M. F.; Eur. J. Org. Chem. 2007, 8, 1324-1331; Dep. Quim., Univ. Minho, P-4710 Braga, Port.; Eng.) -Klein 25-157

Exceedingly facile one-pot protocols to the synthesis of pyrimido annulated analogues of carbazolo condensed azepinones and their evaluation for analgesic activity

“…Literature is replete with examples showing that heterocycles which incorporate carbazoles [1], azepinones [2] and pyrimidines [3] in their molecular framework display wide range of bioefficacies such as anti-cancer [4], anti-leukemic [5], antiproliferative [6], anti-microbial [7], anti-viral [8], anti-malarial [9], antioxidant [10], etc. Ever since, pyrimidine derivatives have been recognized to belong to the class of 'privileged medicinal scaffolds' [11] its potential have been widely exploited in the discovery of such pyrimidine based drugs as 'Etravirine' [12] which has emerged as a highly potent anti-HIV agent, to have found the FDA approval for the treatment of AIDS.…”

“…from easily accessible starting materials, we report herein in this communication, the preliminary results of our study on the synthesis of pyrimidine annulated analogues of carbazolo fused azepinones(8)(9)(10)(11)(12)(13)(14)(15) from 7-ethyl-3,4-dihydroazepino[3,2-b] carbazol-2,5(1H,7H)-dione (3) [18]. A perusal of literature on the preparation of oxoketenedithioacetals, 2-(dimethylaminomethylene) ketones, oxoenolethers and α,βunsaturated ketones (chalcones), demonstrated that these were readily available from the base catalyzed condensation of carbonyl species containing an active methylene group with (i) CS 2 + MeI (ii) DMF-DMA (iii) HCOOEt and (IV) C 6 H 5 CHO respectively.…”

“…Application of this strategy on 3 afforded the intermediates 4-7 in moderate to good yield. The versatility of these novel precursors in heteroannulations of 3 was examined by allowing 4-7 derivatives to react with urea, thiourea, acetamidine and guanidine, which resulted the desired pyrimidine annulated analogues(8)(9)(10)(11)(12)(13)(14)(15) in acceptable yields. Compound 3 was in turn realized from the commercial 3amino-9-ethyl carbazole (1) on its reaction with ethyl succinyl chloride under the conditions of Friedel-Crafts acylation, followed by cyclocondensation of the resulting intermediate with PPA.…”

Americans performing Afro-Brazilian maracatu and afoxé : Navigating Race, Religion, Appropriation, and the Potential of Anti-Racist Pedagogy

“…Tensions emerged between such percussion groups and the longstanding Afrodescendant maracatus-nação in Recife, with activists and maracatuzeiros/as critiquing middle-class interest in and performance of maracatu as cultural appropriation, a critique substantiated by the privileged position of the new percussion groups in the Brazilian media. 20 The debates between maracatus-nação and the middle-class percussion groups highlight the role of musical practices in defining spatio-racial formations in Recife.…”