TITANIUM(IV) CHLORIDE-INDUCED REACTIONS OF KETONES AND C-ACYLIMINES WITH DIMETHYLCYANAMIDE

The reactions of ketones (benzophenone, 4-methylbenzophenone, acetophe none, acetone, and 2,2,4,4-tetramethyl-3-pentanone) and C-acylimines w ith dimethylcyanamide in the presence of titanium(IV) chloride were in vestigated. Benzophenone and 4-methylbenzophenone react with dimethylc yanamide to give 4,4-disubstituted 2-dimethylamino-3-aza-1-oxa-1,3-but adienes 5 and 4,4-disubstituted o-1-N,N-dimethylcarbamoyl-1,3-diaza-1, 3-butadienes 9. Ketones with enolizable hydrogen atoms undergo aldol r eactions under these conditions. C-Acylimines 11b-11e, derived from be nzil and substituted anilines, undergo [2 + 2] cycloaddition to dimeth ylcyanamide with subsequent ring opening to lcarbamoyl)-2,3,4-triaryl- 1,4-diaza-1,3-butadienes 15. 1,2-Diphenyl-2-(isopropylimino)ethanone ( 11a) reacts with dimethylcyanamide to give lamino-1-isopropyl-4,4-diph enyl-2-imidazolin-5-one (23) in a hitherto unknown multistep reaction. The structure of 23 was confirmed by an X-ray analysis.