Three-component synthesis of tetrazolo-pyrimidines annelated by C6 to C8 carbocycles
By treatment of 3-amino-4H-1,2,4-triazole and 5-amino-1H-tetrazole with -unsaturated ketones of cyclohexanone series, we have previously obtained linearly structured azoloquinazolines with an admixture of isomers with angular ring fusion [1]. Extension of this reaction to ylidenecyclohexanone analogs with a greater size of alicycle (C7, C8) was not appropriate due to their low yields. Bearing in mind the importance of substituted azolopyrimidines in the search for novel biologically active materials and the successful use of multicomponent reactions [2, 3] for heterocycle synthesis, we have studied the possibility of using three-component cyclocondensation for synthesis of tetrazolopyrimidines annelated by C6 to C8 carbocycles. The reactions were carried out by refluxing equimolar amounts of the 5-amino-1H-tetrazole, the aldehyde 1a,b (furfural, benzaldehyde), and ketone 2a-c (cyclohexanone, cycloheptanone, cyclooctanone). As a result, the partially reduced cyclanotetrazolopyrimidines 3a-f were obtained in 39-68% yields.