catalyst-free preparation of 4h-1,3,4-oxadiazines in h2o

This report provides a description of a novel and efficient procedure for the synthesis of substituted 4h-1,3,4-oxadiazines via reaction of various vinyl cyanides and acetohydrazide in h2o under catalyst-free conditions. the remarkable advantages are the simplicity of the experimental procedures, high yields, and avoidance of organic solvents. products were characterized by melting point, ir, 1h- and 13c-nmr spectra, and elemental analysis. the desired products were obtained in >85% yields.