No abstract

No abstract

Heterocyclizations of benzoxa(thia)zolyl-2-guanidines with b-dicarbonyl compounds, such as diketones and derivatives of acetoacetic ether, were studied.The high reactivity of guanidine and its derivatives allows them to be brought into a great number of heterocyclizations, thereby preparing azaheterocycles of various degree of complexity [1]. Much evidence is available on the reactions of amidines and guanidines with a,b-unsaturated carbonyl and b-dicarbonyl compounds, leading to pyrimidines and aminopyrimidines [234]. Compounds of these classes exhibit bactericide and antiviral activity, in particular, are anti-HIV preparations [537].The aim of the present work was to study the re-ÄÄÄÄÄÄÄÄÄÄÄÄ activity of benzoxa(thia)zolyl-2-guanidines Ia and Ib in heterocyclizations with b-dicarbonyl compounds: diketones IIa3IIf and keto esters IVa3IVh.To effect condensation of compounds I with diketones requires fairly rigid conditions: boiling for 3310 h (depending on the reactivity of the diketone) in xylene with azeotropic distillation of water. The reaction products, 2-[benzoxa(thia)zol-2-ylamino]pyrimidines IIIa3IIIi, are generally less soluble and precipitate already from a hot reaction mixture or on its cooling. Ia, IbIIa!IIf IIIa!IIIi g H g H I, Q = O (a), S (b); II, R 1 = R 3 = CH 3 , R 2 = H (a); R 1 = R 2 = R 3 = CH 3 (b); R 1 + R 2 = (CH 2 ) 3 , R 3 = CH 3 (c); R 1 + R 2 = (CH 2 ) 4 , R 3 = C 2 H 5 (d); R 1 = CF 3 , R 2 = H, R 3 = CH 3 (e); R 1 = CF 3 , R 2 = H, R 3 = thienyl (f); III, Q = O, R 1 = R 3 = CH 3 , R 2 = H (a); Q = S, R 1 = R 3 = CH 3 , R 2 = H (b); Q = O, R 1 = R 2 = R 3 = CH 3 (c); Q = O, R 1 + R 2 = (CH 2 ) 3 , R 3 = CH 3 (d); Q = S, R 1 + R 2 = (CH 2 ) 3 , R 3 = CH 3 (e); Q = O, R 1 + R 2 = (CH 2 ) 4 , R 3 = C 2 H 5 (f); Q = S, R 1 + R 2 = (CH 2 ) 4 , R 3 = C 2 H 5 (g); Q = O, R 1 = CF 3 , R 2 = H, R 3 = CH 3 (h); Q = S, R 1 = CF3, R 2 = H, R 3 = thienyl (i). ÄÄÄÄÄÄÄÄÄÄÄÄBenzoylacetone under prolonged heating in the above conditions provides only traces of the reaction product. As the reaction time is increased, stronger tarring is observed. Dibenzoylmethane failed to react. The reactivity of the diketones with respect to guanidine I decreases in the order CF

Fused pyrimidine derivatives R 0515 Novel Variant of Recyclization of N-Arylmaleimides When Reacted with Aminoazoles. -(KOVYGIN, Y. A.; KRYLSKI, D. V.; ZORINA, A. V.; SHIKHALIEV, K. S.; Chem. Heterocycl. Compd. (N. Y.) 40 (2004) 9, 1222-1223; Voronezh State Univ., Voronezh 394693, Russia; Eng.) -H. Toeppel 23-158

No abstract

Thiazine derivatives R 0610 Two Directions of Reaction Between Aminothiophenol and 3-Bromoarylmaleimides. -The unexpected outcome of the title reaction leading to compound (IV) as major product is briefly discussed. -(ZORNIKOV, I. P.; SHIKHALIEV*, K. S.; KOVYGIN, Y. A.; SABYNIN, A. L.; ZORINA, A. V.; Russ.

A convenient method for the synthesis of 2-(2-R-5-oxo-6,7-dihydro-4H-[1,2,4]triazolo-[1,5-a] pyrimidin-6-yl)acetanilides based on the regioselective domino reaction of N-arylitaconimides with substituted 3-aminotriazoles was proposed. Presumably, the reaction pathway includes the conjugated aza-addition of the endo-nucleophilic center of triazole to imide, followed by the recyclization of the intermediate to triazolo [1,5-a]pyrimidine.

No abstract