Benzalacetophenone addition reactions

ADDITION REACTIONS OF CARBON-CARBON DOUBLE BONDS double bond of benzalacetophenone, we might write either... 

In a 3-I. round-bottomed, three-necked flask fltted with a liquid-sealed mechanical stirrer, a thermometer, and a 500-cc. separatory funnel are placed 1700 cc. of dry ben2ene and 160 g. (1.2 moles) of powdered, anhydrous aluminum chloride (Note i). The mixture is cooled to 10° by means of an ice-water bath and maintained at 10-20 during the addition of a solution of 120 g. (0.58 mole) of benzalacetophenone (Note 2) (Org. Syn. Coll. Vol. I, 71) in 300 cc. of dry benzene. This addition requires about thirty minutes. The cooling bath is then removed and stirring continued at room temperature until all the dense, yellow precipitate formed at first has gone into solution (Note 3). The reaction is complete after stirring for an additional hour. 

The special and unique reactivities associated with this class of compounds were rapidly recognized. For example, the reaction of Li[Ph3Mg] with benzalacetophenone yields mainly the 1,4-addition product while the same reaction with PhLi affords the 1,2-addition product. Wittig rationalized the chemistry of ate-complexes in terms of anionic activation by which all of the ligands surrounding the metal were activated through an inductive effect. In an early review of structures and reactions of organic ate-complexes by Tochtermann this idea was emphasized. ... 

The addition of malonic ester to benzalacetophenone is an illustration of a very general base-catalyzed condensation. The olefinic compound taking part in the reaction may be one in which the double bond is in the alpha position of an aldehyde, ketone, " ester,... 

There are relatively few reports involving the Michael addition of cyanomethylphosphonate anions to unsaturated compounds. The reaction provides a methodology for the elaboration of new reagents but more frequently is used for the preparation of phosphonylated heterocycles. Under basic conditions, diethyl cyanomethylphosphonate adds to benzalacetophenone and 2-bcnzylidcne-3-methyl-4-nitro-3-thiolene-l,l-dioxide to give the addition products in modest yields.- - - " ... 

Michael addition of l-(alkoxycarbonyl)methylphosphonate anions to unsaturated compounds provides a methodology for the elaboration of new reagents and also for the preparation of phosphonylated heterocycles. Thus, in the presence of basic catalysts, diethyl l-(ethoxycarbonyl)alkyl- and l-(ethoxycarbonyl)methylphosphonates add to a.p-nnsaturatcd esters and nitriles.Addition of diethyl l-(ethoxycarbonyl)methylphosphonates under basic conditions to methyl or ethyl acrylates, acrylonitrile, and benzalacetophenone occurs readily and gives rise to products of addition to one and two molecules of the unsaturated compound (Scheme 8.14). ° - ° Reaction of a-substituted phosphonoacetates with acrylates is less vigorous, and attempts at addition to crotonic and methacrylic esters fail. mi-zos-zos... 

The sodium dianions obtained from acids, treated by NaNH2 in liquid ammonia are easily alkylated (refs. 28-30). These dianions have also been used for Michael addition with benzalacetophenone or ethyl cinnamate. A similar Michael addition (ref. 31) is also observed with the enolate of ethyl phenylacetate (Fig. 4). Nitriles can also be deprotonated with NaNH2 in liquid ammonia. The resulting anion was able to give aldol reaction followed by dehydration (ref. 32) or an alkylation reaction (ref. 33). 

KrOhnke annulation involves the condensation reaction of an a-pyridinium methyl ketone salt such as phenacylpyridinium bromide 191 to an enones such as benzalacetophenone 193 to afford 2,4,6-triphenylpyridine 194 in 90% yield. Krdhnke found that glacial acetic acid and ammonium acetate were the ideal conditions to promote the desired Michael addition. 

Pyridyl lithium gives a small yield of the Michael addition product with benzalacetophenone , as does 4-picolyl sodium with methyl vinyl ketone i2 . In contrast, 2-picolyl sodium forms the carbinol, perhaps because of initial reaction at the nitrogen atom... 

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