Condensation, of acetophenone with

Despite a very unfavorable proton transfer using (35) as an EGB, condensation of acetophenone with an aromatic aldehyde took place within a matter of hours. The reaction led to Q , 8-unsaturated ketones, which underwent the Michael addition with a second equivalent of deprotonated ketone. Scheme 30, [80, 81]. The EGB was generated ex situ. 

Diphenyl-4,10-dicarboxy-6-methyl-l,7-phenanthroline (25) has been obtained179 along with the quinoline derivative (24) by the alkaline condensation of acetophenone with the substituted isatin (23). 

Monodirectional 12 membered ring zeolites (offretite, L, mordenite and 0) are very inefficient as catalysts for formaldehyde benzene condensation to give diphenylmethane, esterification of phenylacetio acid with equimolar amounts of ethanol, Friedel-Crafts acylation of 3-phenylpropanoyl chloride with anisole and Claisen-Schmidt condensation of acetophenone with benzaldehyde. This fact has been attributed to diffusional constraints of organic compounds inside the channels. By contrast, the behaviour of the tridireotional f zeolite is very similar to that of dealuminated HY zeolites, inoreasing the turnover of the acid sites with the framework Si-to-Al ratio. 

In the present paper we have studied four acid catalyzed reaotions involving carbonyl compounds alkylation of benzene with formaldehyde, esterification of phenylacetic acid, Friedel-Crafts acylation by phenylpropanoyl chloride, and the cross aldolic condensation of acetophenone with benzaldehyde in the presence of three Hp zeolites with different framework Si-to-Al... 

Condensation of acetophenone with AT in DMF and catalytic acetic acid (Scheme 13) leads to dihydro TP 49 and byproduct 50 that in the presence of hydrochloric or phosphoric acid becomes the main product (92DOK801). It seems to originate from the hypothetical intermediate 48 by reaction with the solvent DMF. 

In this section, we discuss a useful version of mixed ketone-aldehyde condensation, the reaction of aromatic methyl ketones with nonenolizable (usually aromatic) aldehydes. The prototype reaction is the condensation of acetophenone with benzaldehyde, leading to l,3-diphenylprop-2-en-l-one, chalcone (equation 81). The scope of this reaction is exceedingly broad the Nielsen-Houlihan review enumerates hundreds of examples comprising almost every imaginable combination of substituted acetophenone and aromatic aldehyde. - ... 

Condensations of acetophenones with aliphatic aldehydes are often complicated by side reactions, although some simple cases are known to proceed in good yield (e.g. equation 84). An example of the kind of complications that may arise in such cases is seen in the reaction of acetophenone with isobutyr-aldehyde. Base-mediated reaction at low temperature gives a crude aldol that is dehydrated by heating with phosphoric acid to obtain a 3 1 mixture of a,p- and p,7-unsaturated ketones (equation 85). If the reaction is carried out under more traditional conditions, by heating an alcoholic solution of the reactants... 

C liment.. MJ Garcia. H Primo. J Conna. A. Zeolites as catalysts in organic reactions. Claisen-Schmidt condensation of acetophenone with benzaldehyde. Catalysis Letters, 1990 4.85-91. 

Calcined barium hydroxide is an efficient catalyst for a number of base-mediated reactions. Among these, the Claisen-Schmidt condensation of acetophenones with benzaldehydes occurs in times as short as 10 min at room temperature (Eq. 15). The acetophenone enolate (detected by IR spectroscopy) is formed on the catalyst surface, where the reaction with the aldehyde takes place. The higher activity of the ketone enolate is interpreted by the authors as the result of "an increased vibrational state of the lattice", a formulation close to the mechano-chemical explanation. With the help of selective poisoning experiments, it is concluded that the enolate forms via a SET mechanism. 

Cationic surfactants such as the cetyltrimethylammonium compounds CTACl, CTABr, (CTA)2S04 and CTAOH favor, under weakly alkaline conditions, the Claisen-Schmidt condensation of acetophenones with benzaldehydes (Scheme 7.1), allowing the synthesis of biologically interesting compounds, such as chalcones and flavonols [6,7], in water only. 

Santora et al developed an MIP, which was capable of accelerating a similar reaction, i.e., linking cyclohexadiene with a a P-unsaturated carhonyl compounds (cyclic Diels-Alder reaction). Furthermore, redox reactions, transacylations or the synthesis of lactons have been catalyzed by MIP (see also Table 7.6). For the aldol-condensation of acetophenone with benzaldehyde, a polymer imprinted with a dibenzoylmethane/Co complex was utilized. These approaches may just be the beginning of a broad implementation of catalyticaUy active MIP in chemical synthesis. 

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