Benzyl bromide iodide

Primary alkyl, allylic, and benzylic bromides, iodides, and tosylates react with sodium bis(trimethylsilyl)amide to give derivatives that are easily hydrolyzed to produce amine salts in high overall yields.959... 

The 2-benzyl-sustituted salts 78 were prepared by quaternization of isothiazole 74 with benzyl bromide, iodide, fluorosulfonate and tosylate. 5-Phenylisothiazole 74 (R1 = R2 = H, R3 = Ph) reacted difficultly to salt 27c (10%) but 3,5-diphenyl-isothiazole are resisted quaternization by benzyl halides (27c,78a,b 72JCS(P1)2305 78b-d 65JCS(C)4577 78e 92JPR25, Scheme 23). 

The use of a silicon hydride or a tin hydride in place of molecular hydrogen allows the formylation of aryl halides to proceed under much milder conditions. The reactions of aryl and benzylic bromides/iodides catalyzed by Pd(PPh3)3 in the presence of poly(methylhydrosiloxane) (PHMS) at 80° and 3 atm of carbon monoxide afford the corresponding aldehydes in 48- 96% yields. When l-bromo-4-iodobenzene is used as the substrate, 4-bromobenzaldehyde is formed exclusively in 95% yield (Eq. 61). "... 

The synthesis of halodeoxy sugars has also been achieved by reaction of sugar phosphorodiamido and phosphonamido derivatives with alkyl halides (83). Heating equimolar amounts of 6-(tetraethylphosphoro-diamido)-l,2 3,4-di-0 isopropylidene-D-galactose with methyl iodide (and benzyl bromide) at 140°C. for 4 hours afforded the 6-deoxy-6-iodo (74b) (75%) and 6-bromo-6-deoxy (74c) (56%) derivatives, respectively. 

Alkylation reactions are subject to the same constraints that affect all Sn2 reactions (Section 11.3). Thus, the leaving group X in the alkylating agent R—X can be chloride, bromide, iodide, or tosylate. The alkyl group R should be primary or methyl, and preferably should be allylic or benzylic. Secondary halides react poorly, and tertiary halides don t react at all because a competing E2 elimination of HX occurs instead. Vinylic and aryl halides are also unreactive because backside approach is sterically prevented. 

Yet another approach uses electrolysis conditions with the alkyl chloride, Pe(CO)s and a nickel catalyst, and gives the ketone directly, in one step. In the first stage of methods 1, 2, and 3, primary bromides, iodides, and tosylates and secondary tosylates can be used. The second stage of the first four methods requires more active substrates, such as primary iodides or tosylates or benzylic halides. Method 5 has been applied to primary and secondary substrates. 

Secondary benzylic bromides, allylic bromides, and a-chloro ethers can undergo analogous reactions using ZnBr2 as the catalyst.1 2 Primary iodides react with silyl... 

Route A 1- is very convenient for the substitution of OH groups by bromide or iodide. The reaction conditions are relatively mild (acetonitrile, room temperature, and reflux for 1—3 h, neutral medium). The activating halide (methyl iodide, ally or benzyl bromide) is added in excess (5 equivalents) or in large excess (10 equivalents) when the resultant halide is nearly as reactive as the activating halide. The imidazolium-iV-carboxylates are the important intermediates, which undergo a displacement reaction to give the halides,... 

Alkyl iodides, benzyl chlorides, benzyl bromides, and adamantyl bromides and iodides undergo reduction with triethylsilane/palladium chloride.195 The reduction of a /3-chloro ether occurs in excellent yield with this system (Eq. 56).195... 

A useful extension of the in situ anomerization process involves the employment of C-nucleophiles such as vinyl and allyl magnesium bromides. Grignard reactions to per-O-benzylated glycosyl iodides proceed stereoselectively when a strong nucleophile like allyl magnesium bromide is used, giving [1-C-allyl fucosides (95% P-only)... 

Trevoy and W.G. Brown reported in 1949 that LiAlH4 reduced both benzyl iodide and benzyl bromide at 35° in high yields. The solvents were either ether or THF. The products were toluene. 

N-(l-Methyl- and l-benzyl-3-pyrrolyl)aminomethylenemalonates (1476, R = Me, CH2Ph) were obtained in 91% and 91% yields, respectively, when 3-pyrrolylaminomethylenemalonate (1476, R = H) was reacted with methyl iodide or with benzyl bromide in DMF in the presence of sodium methylate at ambient temperature for 10-60 min (85JHC83 89JHC1029). N-Methyl derivatives (1477) were prepared in nearly quantitative yield under the previous conditions with methyl iodide if the reaction mixtures were stirred overnight. 

The reactions of 3-pyrazolylaminomethylenemalonate (1478, R = R1 = R2 = H) with dimethyl sulfate, ethyl iodide, or benzyl bromide in boiling THF in the presence of sodium hydride yielded -substituted AK3-pyrazolyl)aminomethylenemalonates (1478, R = R1 = H, R2 = Me, Et, PhCH2). 3-Pyrazolylaminomethylenemalonate (1478, R = COOfBu, R1 = R2 = H) was dimethylated with methyl iodide in DMF in the presence of sodium methylate at room temperature overnight to give /V-methyl-N-U -dimethyl-S-pyrazolyDaminomethylenemalonate (1478, R = COOfBu, R1 = R2 = Me) in 88% yield (85JHC729). 

Monoalkylation of optically active 1-phenylethylamine with benzyl bromide in N,N-dimethylpropyleneurea (249a) at 100 °C in the presence of sodium carbonate gives the enantiomerically pure A-benzyl derivative. Isopropyl iodide and neopentyl iodide behave analogously275. 

Functionalized organozinc halides are best prepared by direct insertion of zinc dust into alkyl iodides. The insertion reaction is usually performed by addition of a concentrated solution (approx. 3 M) of the alkyl iodide in THF to a suspension of zinc dust activated with a few mol% of 1,2-dibromoethane and MeaSiCl [7]. Primary alkyl iodides react at 40 °C under these conditions, whereas secondary alkyl iodides undergo the zinc insertion process even at room temperature, while allylic bromides and benzylic bromides react under still milder conditions (0 °C to 10 °C). The amount of Wurtz homocoupling products is usually limited, but increases with increased electron density in benzylic or allylic moieties [45]. A range of poly-functional organozinc compounds, such as 69-72, can be prepared under these conditions (Scheme 2.23) [41]. 

P-Phenethylbiguanide is reported 602) to be resistant to methylation but as it behaves generally somewhat anomalously, e.g. in its stabihty towards acids (Section VII C), this provides no information as to the general behaviour of biguanides on alkylation. Thus, methyl iodide in methanol converted p-phenethylbiguanide merely into its hydriodide, and similar results were observed with methyl tosylate, and benzyl bromide. 

Benzyl-6-methylcyclohexanone has been prepared by the hydrogenation of 2-benzylidene-6-methylcyclohexanone over a platinum or nickel catalyst, and by the alkylation of the sodium enolate of 2-formyl-6-methylcyclohexanone with benzyl iodide followed by cleavage of the formyl group with aqueous base. The 2,6-isomer was also obtained as a minor product (about 10% of the monoalkylated product) along with the major product, 2-benzyl-2-methylcyclohexanone by successive treatment of 2-methylcyclohexanone with sodium amide and then with benzyl chloride or benzyl bromide. Reaction of the sodium enolate of 2-formyl-6-methylcyclohexanone with potassium amide in liquid ammonia formed the corresponding dianion which was first treated with 1 equiv. of benzyl chloride and then deformylated with aqueous base to form 2-benzyl-2-methylcyclohexanone.i ... 

Benzylic halides are reduced very easily using complex hydrides. In a-chloroethylbenzene lithium aluminium deuteride replaced the benzylic chlorine by deuterium with inversion of configuration (optical purity 79%) [537]. Borane replaced chlorine and bromine in chloro- and bromodiphenylme-thane, chlorine in chlorotriphenylmethane and bromine in benzyl bromide by hydrogen in 90-96% yields. Benzyl chloride, however, was not reduced [5iSj. Benzylic chlorine and bromine in a jy/n-triazine derivative were hydrogeno-lyzed by sodium iodide in acetic acid in 55% and 89% yields, respectively [5i9]. 

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