The structure of 2'-cyclohexyl-16 alpha, 17 3]oxazino[5',6':16,17]estr
a-1,3,5(10),16-tetraene, C27H37NO2, synthesized via a Ritter reaction,
is reported. A cis-fused dihydrooxazine ring, condensed to the known
estrane skeleton, was found in the title compound.