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Titanium(IV) Chloride Induced Reactions of Ketones and C ‐Acylimines with Dimethylcyanamide
Author(s) -
Mazik Monika,
Sustmann Reiner,
Boese Roland
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619961027
Subject(s) - benzophenone , chemistry , acetophenone , benzil , medicinal chemistry , cycloaddition , acetone , ketone , benzoyl chloride , chloride , organic chemistry , catalysis
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.