A new method for the synthesis of 1,2,4-triazine 4-oxide derivatives h
as been suggested; this method includes the reaction of isonitrosoketo
ne hydrazones 2 with aldehydes followed by oxidation of 3-R-3,4-dihydr
o-4-hydroxy-6-phenyl-1,2,4-triazines 3 by lead tetraacetate.