Allyl bromide, reaction

Recently, Shiraishi and Goda [161 studied allylation of wood meal with allyl chloride or allyl bromide [Reaction (3)]. 

The synthesis of barbiturate 36 (see Scheme 4.7) was performed next. The sodium enolate of diethyl malonate was reacted with 43, providing 44, which was converted to 2,2-disubstituted malonate 45 by reaction with allyl bromide. Reaction of 45 with urea in the presence of t-BuOK as base afforded the barbiturate 46, which was submitted to oxidative one-carbon demolition by the action of KMn04 to give carboxylic acid 47. Compound 47 was esterified with ethanol to give the target 36, but unfortunately in modest yields. 

When the alkylating agent is a substituted allylic bromide, reaction could occur at either the a- or the y-carbon. Only a-attack is observed and the phosphonium salt (8) from regiospecific alkylation at the less hindered carbon is produced. Again, the two possible regioisomers are distinguishable by virtue of the difference in the multiplicity of their fluorine signals in the 19F NMR spectrum. Salt (8) appears as a doublet of doublet of doublets, whereas (9) would be expected to be a doublet of doublets. 

Etherification of hindered tribromophenol with allyl bromide Reaction of sodium sulfide with benzyl chloride Reaction of amino acids and methanesulfonyl chloride Dichlorovinylation of carbazole in solid-liquid system... 

Etherification of Sucrose Chelates by Allyl Halides, and Sodium Bromoacetate, Allyl bromide or chloride was added to a dimethylsulphoxide (DMSO) solution of sucrose chelate in the ratios of sucrose allyl halide 1 1,1, 1 1,3, 1 2,0 and 1 2,5 and kept at 80°C for 16 to 48 h. The allyl bromide reactions were carried out in screw cap, sealed test tubes and most of the allyl chloride reactions in a sealed autoclave. Decomposition of the sucrose was prevented by keeping the ratio of sucrose to allyl halide equal or less than the ratio 1 2,5. The reaction between sucrose chelates and sodium bromoacetate was performed in the following ratios sucrose bromoacetate, 1 2,6, 1 3,8, 1 5,2 and 1 7,0, in DMSO for 72 h at 70°C. 

It is to be noted that besides allyl bromide, reactions with 3-methylallyl bromide are mentioned in this patent. What was unknown to Knorr at that time is that the products from the organometallic reagent of this halide result from the following allylic rearrangement (see Sect. 2.3.5) ... 

If reaction does not occur when a little allyl bromide is first introduced, further addition must be discontinued until the reaction has commenced. Remove 2-3 ml. of the Grignard solution with a dropper pipette, add about 0-5 ml. of allyl bromide and warm gently to start the reaction after this has reacted well, add the solution to the main portion of the Grignard reagent. 

Nickel-allyl complexes prepared from Ni(CO)4 and allyl bromides are useful for the ole-fination of alkyl bromides and iodides (E.J. Corey, 1967 B A.P. Kozikowski, 1976). The reaction has also been extended to the synthesis of macrocycles (E.J. Corey, 1967 C, 1972A). 

Organoboranes are reactive compounds for cross-coupling[277]. The synthesis of humulene (83) by the intramolecular cross-coupling of allylic bromide with alkenylborane is an example[278]. The reaction of vinyiborane with vinyl-oxirane (425) affords the homoallylic alcohol 426 by 1,2-addition as main products and the allylic alcohol 427 by 1,4-addition as a minor product[279]. Two phenyl groups in sodium tetraphenylborate (428) are used for the coupling with allylic acetate[280] or allyl chloride[33,28l]. 

Indol-2-ylcopper reagents can also be prepared from 2-lithioindoles and they have some potential for the preparation of 2-substituted indoles. 1-Methyl-indol-2-ylcopper can be prepared by reaction of 2-lithio-l-methylindole with CuBr[10]. It reacts with aryl iodides to give 2-aryl-1-methylindoles. Mixed cyanocuprate reagents can be prepared using CuCN[ll], The cyan-ocuprate from 1-methylindole reacts with allyl bromide to give 2-allyl-l-methylindole. 

Kharasch s earliest studies in this area were carried out in collab oration with graduate student Frank R Mayo Mayo performed over 400 experi ments in which allyl bromide (3 bromo 1 propene) was treated with hydrogen bromide under a variety of conditions and determined the distribution of the normal and abnormal products formed during the reaction What two prod ucts were formed Which is the product of addition in accordance with Markovmkovs rule Which one corresponds to addition opposite to the rule ... 

Alkenes react with N bromosuccimmide (NBS) to give allylic bromides NBS serves as a source of Br2 and substitution occurs by a free radical mechanism The reaction is used for synthetic purposes only when the two resonance forms of the allylic radical are equivalent Otherwise a mixture of isomeric allylic bromides is produced... 

Allyl phenyl ether is pre pared by the reaction of phenol with allyl bromide as described in Section 24 11... 

The dianions derived from furan- and thiophene-carboxylic acids by deprotonation with LDA have been reacted with various electrophiles (Scheme 64). The oxygen dianions reacted efficiently with aldehydes and ketones but not so efficiently with alkyl halides or epoxides. The sulfur dianions reacted with allyl bromide, a reaction which failed in the case of the dianions derived from furancarboxylic acids, and are therefore judged to be the softer nucleophiles (81JCS(Pl)1125,80TL505l). 

Allyl ethers can be prepared by reaction of a phenol and the allyl bromide in the presence of base. Several reagents have been used to effect their cleavage ... 

A mixture of 3.18 g (10 mmoles) of 17 -hydroxy-2-hydroxymethylene-5a-androstan-3-one, 20 ml dry dimethyl formamide and 0.3 g (13 mmoles) of sodium hydride is stirred for 0.5 hr at room temperature under nitrogen. A total of 1.51 g (12.5 mmoles) of redistilled allyl bromide is added and the mixture is stirred for 1 hr on the steam bath. Aqueous potassium hydroxide (2 g in 5 ml of water) is added and stirring is continued for 1 hr on the steam bath. The reaction mixture is diluted with 50 ml of methylene dichloride followed by careful addition of 300 ml of water. The organic phase is separated and the aqueous phase is again extracted with 50 ml of methylene dichloride. The combined extracts are washed with water, dried over sodium sulfate, filtered and chromatographed on 200 g of silica gel. Elution with pentane-ether (4 1) provides 2a-allyl-17j -hydroxy-5a-androstan-3-one 0.85 g (26%) mp 118-119° [aj 14° (CHCI3), after crystallization from ether-hexane. 

Perfluoronaphthalene undergoes an intermolecular substitution followed by intramolecular cyclLzation on reaction with allyl bromide and mercaptide ion to furnish a dihydrothiophene denvative in high yield [34] (equation 23). 

One of the advantages of the enamine alkylation reaction over direct alkylation of the ketone under the influenee of strong base is that the major product is the monoalkylated derivative 29,32). When dialkylation is observed, it occurs at the least substituted carbon in contrast to alkylation with base, where the a-disubstituted product is formed. Dialkylation becomes the predominant reaction when a strong organic base is added and an excess of alkyl halide is used (29). Thus 1-N-pyrrolidino-l-cyclo-hexene (28) on treatment with two moles of allyl bromide in the presence of ethyl dicyclohexylamine (a strong organic base which is not alkylated under the reaction conditions) gave a 95 % yield of 2,6-diallylcyclohexanone (29). 

The application of this strategy to the synthesis of chiral cyclohexadienes has been demonstrated by Kiindig. Addition of MeLi to the Cr(CO)3-complexed chiral phenyl oxazoline 43 followed by reaction with allyl bromide produced cyclohexadiene 44 in 69% yield and >98% de. ... 

Few other reactions of series of substituted pyridines have been investigated extensively. Dondoni, Modena, and Todesco have measured the rate of N-oxidation of a limited series of pyridines and found a good correlation with normal u-values with a p-value of — 2.23. The A-alkylation of pyridines with alkyl iodides in nitrobenzene has been studied by Brown and Cahn and by Clarke and Rothwell. Unfortunately, the only data available are for the parent compound and for alkyl derivatives, and, since the a-values for the various alkyl groups in a given position are substantially constant, this leaves a correlation of only three independent points. However, the rates of A-alkylation of the j8- and y-alkyl derivatives are so nearly equal that it appears as if no correlation existed. Clarke and Rothwell have also studied the alkylation with allyl bromide in nitromethane at various temperatures, and in this case a more extensive series is available. The authors state that no overall Hammett correlation is obtained however, the j8-substituted derivatives fall on one straight line and the y-derivatives on another one with a different slope. The data are shown in Fig. 2. The line for the j8-compounds, p = — 2.53 0.31, r = 0.95, is seen not to be very good the line for the y-derivatives, p = — 1.42 0.06, r = 0.99, is much more satisfactory. It does not seem likely that the discrepancy is due to the intervention of resonance effects, since in this case one would expect the correlation for the y-derivatives to be poorer than that for the j8-analogs. More extensive studies with a wider variety of substituents would seem very desirable. 

The allylation reaction of the optically active tetronic acid derivatives 146 was shown to give a variety of isomers depending on the reaction conditions (temperature and reaction time) (Scheme 44 and Table I) (99H1321). The reaction is carried out by treating 146 with allyl bromide in DMF and in the presence of K2CO3. 

Bromination of the diphenyl indole derivative 316 with bromine in DMF or trimethylammonium bromide afforded the 7-bromo derivative 317. Reaction with allyl bromide or its derivatives gave A-allyl derivatives 318 that upon cyclization with palladium acetate gave 7,9-dimethoxy-l,2-diphenylpyrrolo[3,2,l-// ]quinoline derivatives 319 (92T7601) (Scheme 57). 

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