Allyl bromide preparation

Allylie pyrophosphates. Primary allylic bromides (prepared by reaction of the alcohol with PBr3) can be converted into the corresponding pyrophosphate esters by reaction with this reagent in 46-54% overall yield (equation 1). 

The allyl bromide (Section 111,35) should be dried over anhydrous calcium chloride and redistilled the fraction b.p. 69-72° is collected for use in this preparation. 

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). 

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. 

A 20% excess of ethylmagnesium bromide was prepared from magnesium (6.5 g) in ether (80 ml) by adding ethyl bromide (30 g) in ether (30 ml). Indole (25.8 g) in benzene (50 ml) was then added slowly with stirring and stirring was continued for 20 min after addition was complete. A solution of allyl bromide (29.2 g) in benzene (20 ml) was then added slowly. The mixture was stirred overnight and then diluted with ether and the product isolated and purified by distillation (22.7 g, 70% yield). 

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 ... 

Pentadiene has been prepared by the interaction of allyl bromide and vinyl bromide in the presence of magnesium and by the pyrolysis of 1,5-pentanediol diacetate or 4-penten-l-ol acetate. The present procedure is essentially that of Shoemaker and Boord with some modifications. ... 

Similar methodology has been used to prepare the dialkoxyphosphinyldi-fluoromethylcopper compound 242 (equation 160) Functionalization with allyl bromide, methyl iodide, and iodobenzene occurs readily, as well as stereospecific syn addibon to hexafluoro-2-butyne [243. ... 

Allyl phenyl ether is prepared by the reaction of phenol with allyl bromide, as described in Section 24.11. 

Allyl bromide, K2CO3, THF, heat, 75% yield." This is a fairly general method that has been used widely for the preparation of allylamines. 

We first tried to prepare 1-hydroxyyohimbine (23) and its derivatives. With 23 in hand (as described in Section II.D), its methylation with CH2N2 is carried out to provide 1-methoxy derivative 304 (77%) (Scheme 47). Utilizing K2CO3 as a base in DMF, allyl bromide, butyl iodide, and p-nitrobenzyl bromide react successfully with 23, resulting in the formation of 305 (93%), 306 (99%), and 307 (90%), respectively. All of these compounds, including 23 itself, are found to exhibit potent Q 2-blocking activity (2001H1237), and the details will be reported in due course. 

Preparation of the aldehyde required for the synthesis of cyclothiazide (182) starts by carbonation of the Grignard reagent obtained from the Diels-Alder adduct (186) from allyl bromide and cyclopentadiene.The resulting acid (187) is then converted to the aldehyde (189) by reduction of the corresponding diethyl amide (188) with a metal hydride. 

In the preparation of the thiazides containing more highly functionalized side chains (183-185), an acetal of the aldehyde is usually used rather than the free carbonyl compound. Thus, trichlomethiazide (183) is prepared by reaction of 160 with the dimethyl acetal from dichloroacetaldehyde. In a similar vein, alkylation of the acetalthiol, 190, with allyl bromide affords 191. This yields altizide (184) on condensation with 160. Alkylation of 190 with 2,2,2-trifluoroethyl iodide gives 192. This leads to epithiazide (185) on condensation with 160. 

Preparation of Diethyl Allyl (1-Methyl-2-Pentynyl) Malonate A solution of 12.1 g of sodium in 182 ml of absolute ethanol was prepared, and thereto were added 126.6 g of diethyl (1-methyl-2-pentynyl) malonate. Most of the ethanol was then distilled off under reduced pressure, and the residue was cooled and 63.5 g of allyl bromide were slowly added thereto. After completion of the addition, the mixture was refluxed for about 1 hour. 

Propyl-methyl-carbinyl allyl barbituric acid (also called allyl 1-methyl-butyl barbituric acid) may be prepared as follows 1 mol of propyl-methyl-carbinyl barbituric acid is dissolved in a suitable vessel In a 10 to 35% aqueous solution of 1 mol of potassium hydroxide. To this are added somewhat in excess of 1 mol of allyl bromide, and alcohol equal to about 10% of the total volume of the solution. The vessel Is agitated for 50 to 75 hours. At the end of this time, the solution, which may still exhibit two layers, is concentrated to about one-half its volume to remove the excess allyl bromide and the alcohol. On cooling, an oily layer, which is propyl-methyl-carbinyl allyl barbituric acid, separates out as a sticky viscous mass. It is dried, washed with petroleum ether, and dissolved in the minimum amount of benzene. Any unreacted propyl-methyl-carbinyl barbituric acid, which does not dissolve, is filtered off. The addition of petroleum ether to the clear filtrate causes the propyl-methyl-carbinyl allyl barbituric acid to precipitate as an oily mass. 

B) Preparation of 7-A//y/oxy-4,8-Dimethylcoumarin 7-Hydroxy-4,8-dimethylcoumarin (191.3 g, 1.01 mols), anhydrous potassium carbonate (604 g, 4.37 mols), and allyl bromide (578 ml, 6.22 mols) were refluxed overnight in acetone (ca 3 liters) with mechanical stirring. The reaction mixture was concentrated nearly to dryness on a steam bath under re-... 

B. Preparation of Allyl Cyanide.— In a i-l. round-bottom flask fitted with a condenser (Note 4) and a mechanical stirrer are placed 220 g. (1.83 moles) of allyl bromide (Note 5) and 170 g,... 

Allyl cyanide has been found in oil of mustard 1 and has been prepared from allyl chloride and potassium cyanide,2 allyl bromide and potassium cyanide,3 allyl iodide and potassium cyanide4 and silver cyanide.5 The method described in the procedure is essentially that of Bruylants, who has shown that the yields are much better when dry cuprous cyanide is treated with allyl bromide.6... 

A mixture of 10 mmol of the allyl bromide and 10-15 mmol of the aldehyde, dissolved in 20 mL of THF, is added dropwise at — 5 to 0°C to the chromium(II) chloride solution in THF prepared by method A or B. The mixture is stirred for 36 h at this temperature and then 15 mL of sat. sodium hydroxide and 20 g of anhyd Na2S04 are added stirring is continued for 20 min at 201C. The mixture is filtered over a pad of Celite/Na2S04 (7 l). The filtrate is concentrated and the residue purified, usually by chromatography on silica gel with pentane/diethyl ether or hexane/ethyl acetate. 

Ethoxy-l,3,2-oxazaphospholidine 59 was prepared as a single diastereomer from (-)ephedrine (42) and ethyl dichlorophosphite 57. Its Arbusov reaction with allyl bromide gave the corresponding allyl phosphonates 61a,b as a diastereomeric mixture which could be separated by flash column chromatography and crystallization (Scheme 21) [48], On applying a similar protocol, starting from... 

Similar reactions occur with all aliphatic halides and the rates of substitution are related to the degree of ionic character of the carbon-halogen bond. For preparation purposes, trityl bromide or propargyl bromide are more convenient than allyl bromide. The compounds obtained are listed in Table XI. They were obtained pure and characterized fully. Zr (allyl) 3Br and Zr(allyl)2Br2 are sufficiently soluble in toluene for polymerizations to be initially homogeneous. Their relative reactivities are listed in Table XI. In all cases hydrogen was used to reduce the molecular weight of the polymer formed. In this respect the polymer derived from Zr (allyl )3Br was more readily modified than that from Zr (allyl) 4, but in order to avoid... 

Diterpenoids related to lambertianic acid were prepared by intramolecular cyclization of either an alkene or an alkyne with a furan ring <2005RJ01145>. On heating amine 101 with allyl bromide, the intermediate ammonium ion 102 was formed which then underwent [4+2] cycloadditions in situ to give the spiroazonium bromides 103 and 104 (Scheme 13). These isomers arose from either endo- or co-transition states. The analogous reaction was also carried out with the same amine 101 and propargyl bromide. The products 105 and 106 contain an additional double bond and were isolated in 58% yield. The product ratios of 103 104 and 105 106 were not presented. 

There are few reports of oxidative addition to zerovalent transition metals under mild conditions three reports involving group 10 elements have appeared. Fischer and Burger reported the preparation of aTT -allylpalladium complex by the reaction of palladium sponge with allyl bromide(63). The Grignard-type addition of allyl halides to aldehydes has been carried out by reacting allylic halides with cobalt or nickel metal prepared by reduction of cobalt or nickel halides with manganese/iron alloy-thiourea(64). 

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