A green, inexpensive and efficient organocatalyzed procedure for aqueous aldol condensations

Abstract

É apresentado um procedimento simples e geral para a condensação aldólica cruzada dupla de cetonas cíclicas com vários aldeídos aromáticos catalisada por dietilamina em condições aquosas. Foram obtidos 3,5-bisarilmetilidenos de cetonas homocíclicas e heterocíclicas em um procedimento one-pot em excelentes rendimentos. Além disto, a metodologia é aplicada eficientemente à síntese de chalconas a partir das metil cetonas correspondentes. Na maioria dos casos estudados, os produtos precipitam das misturas de reação e o meio é reciclado em várias reações subseqüentes sem perda significativa de atividade.A facile and general procedure is presented for diethylamine-catalyzed double crossed aldol condensation of cyclic ketones with various aromatic aldehydes under aqueous conditions. Excellent yields of 3,5-bisarylmethylidenes of homocyclic and heterocyclic ketones are achieved in a one-pot procedure. Furthermore, the methodology is efficiently applied to the synthesis of chalcones from their corresponding methyl ketones. In the majority of the cases studied, products precipitate from the reaction mixtures and the medium is recycled in subsequent several reactions without significant loss of activity.

Antiselective Three‐Component Mannich Reactions in Thiopyran‐4‐one System

“…Recently Hashemi's group reported an anti stereoselective synthesis of β‐amino ketones via direct Mannich reactions of cyclic ketones catalyzed by ZrOCl 2 ·8H 2 O , where reactions completed in relatively very short time periods. Base on this report, we were persuaded to apply the results to those heterocyclic systems which have been under our investigations in recent years . Thiopyran‐4‐one 1 was chosen as an appropriate probe to evaluate this idea.…”

An Efficient Friendly Process for Synthesis of (2e, 6e)-2, 6-Bis (4-Nitrobenzylidene) Cyclohexanone a Drug Against Dormant Version of the Mycobacterium Tuberculosis H37ra

“…This reaction is classically carried out using strong acid or base [9]. Indeed, different organometallic complexes, Lewis acid are found to be able to catalyze this reaction [10]. However, most of the above-mentioned process generated a large amount of toxic waste and involved tedious separation procedures since the reactions were homogeneous and the catalysts were destroyed or discarded on the work-up procedure [11].…”