Abstracto‐Nitro‐nitrosobenzene and 3‐nitro‐4‐nitrosotoluene were reacted with 1,3‐butadiene and 2,3‐dimethyl‐1,3‐butadiene to form 3,6‐dihydro‐1,2‐oxazines, in high yields.Infrared spectra, measured in KBr pellets, of starting materials and adducts indicate coplanarity of the nitrogroup and the benzene ring for the starting materials, and considerable steric inhibition of the mesomeric interaction between the nitro group and the benze