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■ Studies on as-Triazine Derivatives. IV. Synthesis of Unsymmetrical 5,6-Disubstituted 1,2,4-Triazines

Shoetsu Konno, Mataichi Sagi, Mitsuko Agata, Yuichi Aizawa, and Hiroshi Yamanaka*

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan

Abstract

The reaction of 5-chloro-6-methyl-3-phenyl-1,2,4-triazine (4a) with ethylidenetriphenylphosphorane followed by the hydrolysis of the resulting as-triazinylphosphorane afforded 5-ethyl-6-methyl-3-phenyl-1,2,4-triazine (6a) in 88 % yield. The condensation of 5-chloro-6-ethyl-3-phenyl-1,2,4-triazine (4b) with dimethyloxosulfonium methylide and subsequent desulfurization of the resulting triazinylmethylide gave 6-ethyl-5-methyl-3-phenyl-1,2,4-triazine (6g) in 32 % overall yield. Using these triazines (6a,6g) as standard specimens, the ratio of isomers (6a,6g) formed from the condensation of 2,3-pentanedione with benzamidrazone, was determined to be 3:1.