
%0 Journal Article
%A Collins, DJ 
%A Hughes, TC 
%A Johnson, WM 
%T Regiospecific Syntheses of the Monomethylated 3-Phenyldihydro-1,2,4-triazin-6(1H)-ones
%J Australian Journal of Chemistry
%D 1996/04/01
%V 49
%N 4
%P 463-468
%K 
%R https://doi.org/10.1071/CH9960463
%U https://www.publish.csiro.au/paper/CH9960463 
%X Unambiguous syntheses of four unreported monomethylated derivatives of 3-phenyldihydro-1,2,4-triazin-6(1H)-ones, namely, the 1-methyl (2), 2-methyl (3), 4-methyl (4) and the imidic O-methyl derivative (5), are described. Regioselectivity was achieved for the synthesis of (2) by addition of ethyl glycinate to the 1,3-dipolar nitrile imine derived from N- methylbenzohydrazonoyl bromide hydrobromide (8). The key step for the synthesis of (3) was addition of benzyl 3-methylcarbazate (14) to ethyl N-[ chloro (phenyl) methylene ] glycinate (15b). The 4-methyl compound (4) was prepared by cycloaddition of ethyl N-( thiobenzoyl ) sarcosinate (21) with hydrazine hydrate, and the O-methyl compound (5) was prepared by reaction of sodium methoxide with 6-chloro-3-phenyl-4,5-dihydro-1,2,4-triazine (23). 
