M. Mazik et al., REACTION OF 1,2-DIKETONES WITH N,N-DIMETHYLCYANAMIDE IN THE PRESENCE OF TITANIUM(IV) CHLORIDE, Tetrahedron, 52(11), 1996, pp. 3939-3946
In the presence of titanium(IV) chloride 1,2-diketones undergo [2+2] c
ycloaddition to N,N-dimethylcyanamide with subsequent ring opening to
bamoyl-2,3-disubstitute-1-oxa-4-aza-1,3-butadienes 5 and bamoyl)-2,3-d
isubstituted-1,4-diaza-1,3-butadienes 10.