S. Jacquot et al., Reaction of diphenyldiazomethane with N-methyloxy- and N-ethyloxycarbonyl-N-(2,2,2-trichloroethylidene)amines, EUR J ORG C, (7), 1999, pp. 1541-1544
Reaction of the title imines with diphenyldiazomethane gives a Delta(3)-1,3
,4-triazoline, which leads, after loss of dinitrogen, to a transient azomet
hine ylide. Subsequent elimination of ethyl or methyl chloroformate gives t
he unexpected 1,1-diphenyl-4,4-dichloro-2-aza-1,3-butadiene.