Allyl bromide reaction with alcohols

Another important metal for Barbier-type reaction is samarium. Allyl bromide reacts with a ketone and Sm to give the homoallylic alcohol. Samarium compounds, such as Sml2, can also be used with allylic halides. 

Solvolysis kinetics of allyl bromide in several alcohols have been studied. Kinetics of the reaction of methyl iodide with a solvatochromic vinylogous a-pyridone have been studied in various solvents. There is a limited relationship of rate to the position of the CT band of the dye. 

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]. 

Me3SiCH2CH=CH2i TsOH, CH3CN, 70-80°, 1-2 h, 90-95% yield. This silylating reagent is stable to moisture. Allylsilanes can be used to protect alcohols, phenols, and carboxylic acids there is no reaction with thiophenol except when CF3S03H is used as a catalyst. The method is also applicable to the formation of r-butyldimethylsilyl derivatives the silyl ether of cyclohexanol was prepared in 95% yield from allyl-/-butyldi-methylsilane. Iodine, bromine, trimethylsilyl bromide, and trimethylsilyl iodide have also been used as catalysts. Nafion-H has been shown to be an effective catalyst. 

One gram of 6,7-dihydro-5H-dibenz[c,e] azepine hydrochloride was dissolved in water, made alkaline with concentrated ammonia, and the resultant base extracted twice with benzene. The benzene layers were combined, dried with anhydrous potassium carbonate, and mixed with 0.261 g of allyl bromide at 25°-30°C. The reaction solution became turbid within a few minutes and showed a considerable crystalline deposit after standing 3 A days. The mixture was warmed VA hours on the steam bath in a loosely-stoppered flask, then cooled and filtered. The filtrate was washed twice with water and the benzene layer evaporated at diminished pressure. The liquid residue was dissolved in alcohol, shaken with charcoal and filtered. Addition to the filtrate of 0.3 gram of 85% phosphoric acid in alcohol gave a clear solution which, when seeded and rubbed, yielded 6-allyl-6,7-dihydro-5H-dlbenz[c,e] azepine phosphate, MP about 211°-215°C with decomposition. 

Later, Torii et al. found that the tin-aluminum-mediated allylation can be carried out with the less expensive allyl chloride, instead of allyl bromide, when a mixture of alcohol-water-acetic acid was used as the solvent.77 When combined with stoichiometric amounts of aluminum powder, both stoichiometric and catalytic amounts of tin are effective. As reported by Wu et al., higher temperatures can be used instead of aluminum powder.78 Under such a reaction condition, allyl quinones were obtained from 1,4-quinones, followed by oxidation with ferric chloride. Allylation reactions in water/organic solvent mixtures were also carried out electrochemically, with the advantage that the allyltin reagent could be recycled.79... 

The indium-mediated allylation of trifluoroacetaldehyde hydrate (R = H) or trifluoroacetaldehyde ethyl hemiacetal (R = Et) with an allyl bromide in water yielded a-trifluoromethylated alcohols (Eq. 8.56).135 Lanthanide triflate-promoted indium-mediated allylation of aminoaldehyde in aqueous media generated (i-airiinoalcohols stereoselectively.136 Indium-mediated intramolecular carbocyclization in aqueous media generated fused a-methylene-y-butyrolactones (Eq. 8.57).137 Forsythe and co-workers applied the indium-mediated allylation in the synthesis of an advanced intermediate for azaspiracids (Eq. 8.58).138 Other potentially reactive functionalities such as azide, enone, and ketone did not compete with aldehyde for the reaction with the in situ-generated organo-indium intermediate. 

Sb. Commercial antimony metal, in aqueous 1 M HC1 or DC1 solution, reacts with allyl bromide and aldehydes to give the corresponding homoallylic alcohols in good yield. The reaction proceeds through the formation of allylstibine intermediates.179 The same allylation can be... 

R1 to R3 with yields ranging from 20% to 90%. For the reaction of acetophenone, allyl bromide can be replaced with propargyl bromide, benzyl bromide, or an a-bromoester, affording the corresponding tertiary alcohols in 86%, 86%, and 66% yields, respectively. 

Carbanions, generated by the reaction of benzylsilanes with tetra-n-butylammo-nium fluoride react with non-enolizable aldehydes to produce the alcohol [67], When a stoichiometric amount of the ammonium fluoride is used, the methylarene corresponding to the benzylsilane is frequently a by-product and arises from formation of the hydrogen difluoride salt during the reaction. When only catalytic amounts of the ammonium fluoride initiate the reaction, the formation of the methylarene is suppressed. In a similar type of reaction (although the mechanism is not known) between aldehydes and ketones, allyl bromide, and tin in the presence of trimethylsilyl chloride the yield of the but-l-en-4-ol is raised significantly by the addition of tetra-n-butylammonium bromide, particularly in the reactions with... 

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