Titanium(IV) Chloride Induced Reactions of Ketones andC-Acylimines with Dimethylcyanamide

✍ Scribed by Mazik, Monika ;Sustmann, Reiner ;Boese, Roland

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 730 KB
• Volume: 1996
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199619961027

✦ Synopsis

Abstract

The reactions of ketones (benzophenone, 4‐methylbenzophenone, acetophenone, acetone, and 2,2,4,4‐tetramethyl‐3‐pentanone) and C‐acylimines with dimethylcyanamide in the presence of titanium(IV) chloride were investigated, Benzophenone and 4‐methylbenzophenone react with dimethylcyanamide to give 4,4‐disubstituted 2‐dimethylamino‐3‐aza‐1‐oxa‐1,3‐butadienes 5 and 4,4‐disubstituted 2‐dimethylamino‐1‐N,N‐dimethylcarbamoyl‐1,3‐diaza‐1,3‐butadienes 9. Ketones with enolizable hydrogen atoms undergo aldol reactions under these conditions. C‐Acylimines 11b–11e, derived from benzil and substituted anilines, undergo [2 + 2] cycloaddition to dimethylcyanamide with subsequent ring opening to 1‐(N,N‐dimethylcarbamoyl)‐2,3,4‐triaryl‐1,4‐diaza‐1,3‐butadienes 15. 1,2‐Diphenyl‐2‐(isopropylimino)ethanone (11a) reacts with dimethylcyanamide to give 2‐dimethylamino‐1‐isopropyl‐4,4‐diphenyl‐2‐imidazolin‐5‐one (23) in a hitherto unknown multistep reaction. The structure of 23 was confirmed by an X‐ray analysis.