ChemInform Abstract: 1‐Arylideneamino‐2,2,2‐trichloroethanols as Synthetic Equivalents of Arylideneimines in the Reaction with Cyclopropenone Derivatives.

Abstract

The title compounds (III) and (VII) react regiospecifically with cyclopropanones to give 2,2′‐diaryl‐tetrahydrobipyrrole‐3,3′‐dione derivatives.

Stable synthetic equivalents of N-unsubstituted imines: Part 1. Synthesis

“…It was shown recently [162] that crystalline compounds (IX) [X = Cl 3 CCH(OH)] may be used as the stable and available synthetic analogs of N unsubstituted arylideneimines. The trichloroetanol fragment is rather labile and is removed simultaneously with the target transformation under the action of solvent (methanol).…”

“…The trichloroetanol fragment is rather labile and is removed simultaneously with the target transformation under the action of solvent (methanol). Arylideneimines (IX) are obtained in moderate to high yields (48-90%) (a) by the reaction of a solution of the appropriate aromatic aldehyde and trichloroacetic aldehyde (chloral) with ammonia gas on cooling and catalysis by Lewis acids (anhydrous ZnCl 2 ) and Brönsted acids (NH 4 Cl, p toluene sulfonic acid) [162] or without catalyst [163,164]; and (b) by the condensation of the preliminarily obtained adduct of chloral with ammonia, which seems to be a mixture of compounds [165,166], and aro matic aldehyde at ambient temperature in the presence of p toluenesulfonic acid [162] or without catalyst [165] (Scheme 45). The second approach provides higher yields and makes it possible to obtain com pounds (IX) with strong electron withdrawing substituents, for example 4 nitrophenyl [162].…”