Synthesis and Preliminary Biological Properties Assessment of Novel 2-S-, 4-, 5-Substituted and Bicyclic Derivatives of 6-Methylpyrimidine-4-ol

Abstract

: A series of novel 2-S-, 4-, 5-substituted and bicyclic 6-methylpyrimidine-4-ol derivatives including pyrazole, 1,2,4-triazole and pyridazine moieties in the molecule were synthesized by accessible and efficient methods. Thiopyrazolyl derivatives were obtained from 2-mercapto-6-methylpyrimidin-4-ol. 4-Triazolyl and 4-aminotriazolylpyrimidines were synthesized from the quaternary ammonium salt of pyrimidine and 4-chloro-substituted 2-thiomethyl-6-methylpyrimidine, respectively. The reaction of potassium salt of 1-methyl-6-oxo-1,6-dihydropyridazin-3-ole with ethyl 2-chloro-3-oxobutanoate and subsequent treatment with thiourea led to 6-((4-hydroxy-2-mercapto-6-methylpyrimidin-5-yl)oxy)-2- methylpyridazin-3 (2H)-one. The reaction product of the latter with 3-chloropentan-2,4-dione was subjected to heterocyclization, which afforded the target bicyclic derivative of pyrimidine. The synthesized compounds showed a pronounced stimulating action on plants growth. Their growth stimulant activities were in the range of 60-93% compared to heteroauxin.