Benzalacetophenone reactions

Place a solution of 10 -4 g. of benzalacetophenone, m.p. 57° (Section IV,130) in 75 ml. of pure ethyl acetate (Section 11,47,15) in the reaction bottle of the catalytic hydrogenation apparatus and add 0 2 g. of Adams platinum oxide catalyst (for full experimental details, see Section 111,150). Displace the air with hydrogen, and shake the mixture with hydrogen until 0 05 mol is absorbed (10-25 minutes). Filter oflF the platinum, and remove the ethyl acetate by distillation. RecrystaUise the residual benzylacetophenone from about 12 ml. of alcohol. The yield of pure product, m.p. 73°, is 9 g. 

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. 

A solution of 20.8 g. (0.1 mole) of benzalacetophenone (Note 1) (Org. Syn. 2, 1) in 150 cc. of c.p. ethyl acetate (Note 2) is placed in the reaction bottle of the catalytic reduction apparatus (p. 10) and 0.2 g. of platinum oxide catalyst (p. 92) is added. The apparatus is evacuated, then filled with hydrogen, and the mixture shaken with hydrogen until 0.1 mole has been absorbed. The time required is usually about fifteen to twenty-five minutes (Note 3). The platinum is filtered off and the solvent removed from the filtrate by distillation. The benzylacetophenone is recrystallized from about 25 cc. of alcohol and melts at 72-730. The yield is 17-20 g. (81-95 per cent of the theoretical amount). 

Ordinary Grignard reagents react with a, -unsaturated carbonyl compounds and afford both 1,2-adduct and 1,4-adduct. However, methylsulfonyhnethylmagnesium bromide or p-tolylsulfonylmethylmagnesium bromide gave only 1,2-adducts in the reaction with conjugated carbonyl compounds such as crotonaldehyde, cinnamaldehyde, trans-4-phenyl-3-buten-2-one, benzalacetophenone and l,5-diphenyl-2,4-pentadien-l-one. 

An extensive paper by Burgada et l. reports the reactions of cyclic phosphites (75 ab) and cyclic phosphoramidites (76 ab) with trans-1,2-dibenzoylethene, methyl fumarate, benzalacetone (PhCH=CH COMe), methyl-4-keto-pent-2-enoate (MeCO.CH=CH.COgMe) and benzalacetophenone (PhCH=CHCOPh)95. These reactions lead to... 

In view of the reaction behavior of l,2 i.5-oxaphosphetanes (22), treated above, it appears fitting to reconsider the mechanism of the hydroxylion induced fragmentation of p-bromophosphinic acid 6443). It was assumed that formation of the phosphinate 65 is followed by that of the four-membered heterocycle 66, which spontaneously decomposes to benzalacetophenone and phenyldioxophosphorane the latter then adds water to give the phosphonie acid 43 ... 

It is interesting to note that the reaction of trans-henzal-acetophenone with ylide 162a affords (15, 25 )-phenylcyclopropane with 35.3% optical purity, whereas its enantiomer having the (li ,2/ )-configuration is formed when tranj-benzalacetophenone is reacted with ylide 162b. Studies on the relationship between the steric requirements of the substituents attached to the chiral ylide sulfur atom and the optical purity of the cyclopropane rings formed have shown that increases in the steric size of the iV,iV-dialkylamino... 

A similar process with benzalacetophenone results in different products, the chemoselectivity being controlled by the experimental conditions, namely the solvent and the supporting electrolyte used [261]. Either an acyclic disulfide, bis(2-benzoyl-l-phenylvinyl) disulfide (in Et0H-DMF/Mg(Cl04)2), or two isomeric thiophenes (in DMF/NaCl04) can thus be obtained (Scheme 63). Upon the substitution of a vinylic proton at C(2) with Br, the reaction becomes more regioselective and the only product now formed is an a,a -dibenzoyl thiophene derivative. 

Noteworthy features of these reactions are the high predominance of E stereochemistry in the case of aldehydes and the good results obtained even with highly enolizable ketones (such as cyclopentanone), a, -epoxy ketones (isophorone oxide) and a,j8-unsaturated compounds (benzalacetophenone and cinnamaldehyde). 

W-alkylperimidines 940 also undergo condensation reactions at the 6- and 7-positions with acylating species such as benzalacetophenone, to give quaternary salts 942 after aromatization of the intermediate 941 <2002RCB139>. 

The quaternary salts 942 are susceptible to oxidative hydroxylation to give l-alkylbenzo[g, ]perimidin-2-ones 943, and the same product can also be obtained by reaction of l-methyl-2-perimidone 944 with benzalacetophenone in PPA <2002RCB139, 2004RJ0895>. 

In contrast to these vapour-phase reactions, it has been reported that ketones and aqueous ammonia (or ammonium acetate) in an autoclave give less complex mixtures of pyridines. Crotonaldehyde gives 5-ethyl-2-methylpyridine (570) in up to 59% yield, methyl vinyl ketone gives 2,3,4-trimethylpyridine (571) rather than 2,3,6-trimethylpyridine 1,3,3-trimethoxybutane has been used in place of methyl vinyl ketone (49JA2629). In some cases reverse aldol reactions occur (for example with benzalacetophenone) giving unwanted products. A similar reverse aldol is responsible for the production of triarylpyridines (572) when benzalacetophenones are treated with formamide and ammonium formate (73JA4891). 

Reaction of l-aryl-3-carbethoxy-6-phenyl-l,4,5,6-tetrahydropyridazin-4-ones 718 with activated olefins such as benzalacetophenone, benzalacetone, 3-benzylideneacetylacetone, diethyl 2-benzylidenemalonate, and a-cyano-/3-phenylacrylic acid in the presence of an organic base like pyrrolidine, morpholine, piperidine, or triethylamine gave the corresponding 2,8-dihydro-l//-pyrano[2,3-t7 pyridazines 719-723, respectively. The 1-oxo- and 1-imino derivatives of the pyrano[2,3-r/ pyridazine ring system were also prepared from the respective 6-oxo or 6-imino derivative of the starting pyridazine 718 under the same conditions (Equation 60) <1989IJB733>. 

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. ... 

Sufficient alcohol is used to dissolve the benzaldehyde rapidly, as well as to retain the benzalacetone in solution until it has had time to react with the second molecule of aldehyde. Lower concentrations of base slow up the formation of the dibenzalacetone and thus favor side reactions which tend to yield a sticky product. Higher concentrations of base give added difficulty in washing. These concentrations were suggested by, and are approximately the same as, those used in the preparation of benzalacetophenone described in Org. Syn. 7, r. 

Gilman and coworkers220 229 235,243 found that PhsGeLi could be added to 1,1-diphenylethylene, 1 -octadecene and benzalacetophenone (but not to 1 -octene, cyclohexene and E-stilbene). The reaction of Ph3GeLi with enolizable ketones followed equation l244. 

Tamura and coworkers investigated the reaction of dianions of f) -ketosulfoxides with electrophiles (Table 9)35. They found that the reaction of the dianions with benzyl bromide, benzophenone, benzaldehyde, benzalaniline, ethyl benzoate and benzalacetophenone resulted in the exclusive formation of a-substituted /S-ketosulfoxides. 

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,... 

The formation of cyano ketones by this method is illustrated by the conversion of phenacyl halides to the corresponding nitriles. Ring closure to cyclopropane derivatives is a side reaction which has been encountered with y-halo ketones. Benzalacetophenone dibromide is converted by alcoholic potassium cyanide to the fi-cyaao ketone, the a-halogen atom being reduced. Several a-chloro ketones have been found to yield a-cyano epoxides. ... 

Most of the discussion of the Baeyer-Villiger reaction of unsaturated ketones is devoted to a,(3-unsaturated ketones, such as mesityl oxide [254], benzalacetophenone [307, and, especially, benzalacetone [25S], The oxidation of ionones does not involve the Baeyer-Villiger reaction and is, therefore, discussed elsewhere (see equations 440 and 441). 

To a solution of 1.0 g (0.048 mol) of benzalacetophenone in 7.5 mL of pyridine is added 11 mL of a fresh 5.25% solution of sodium hypochlorite (Clorox). An exothermic reaction is accompanied by the almost immediate fading of the yellow color of the solution. When the inixtur becomes almost colorless, 25 mL of water is added. The precipitated whiteVystals of the epoxide are filtered with suction, washed thoroughly with water, and recrystallized from ethanol to give 1.0 g (94%) of l,3-diphenyl-2,3-epoxy-l-propanone, mp 89-90 °C. 

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

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