Hydrocarbons reductive alkylation treatment

Secondary Alkyl Alcohols. Treatment of secondary alkyl alcohols with tri-fluoroacetic acid and organosilicon hydrides results only in the formation of the trifluoroacetate esters no reduction is reported to occur.1,2 Reduction of secondary alkyl alcohols does take place when very strong Lewis acids such as boron trifluoride126 129 or aluminum chloride136,146 are used. For example, treatment of a dichlo-romethane solution of 2-adamantanol and triethy lsilane (1.3 equivalents) with boron trifluoride gas at room temperature for 15 minutes gives upon workup a 98% yield of the hydrocarbon adamantane along with fluorotriethylsilane (Eq. 10).129... 

Although the synthetic yields of hydrocarbon products obtained from the reduction of tertiary alkyl alcohols are frequently quite high, studies show that the reaction pathways taken by the reactants are not always as direct or straightforward as might be suggested by the structural relationships between reactants and products. For example, preparative-scale treatment of a dichloromethane solution of 3-ethylpentan-3-ol and triphenylsilane (1.2 equivalents) with excess trifluo-roacetic acid (1.5 M) at room temperature for 24 hours gives 3-ethylpentane in 78% yield (Eq. 14).127 Under these reaction conditions, the alcohol rapidly... 

Bromoadamantane and 1-bromoadamantane are reduced to adamantane in yields of 84% and 79%, respectively, when treated with triethylsilane and catalytic amounts of aluminum chloride.186 Similar treatment of benzhydryl chloride and exo-2-bromonorbomane gives the related hydrocarbons in yields of 100% and 96%, respectively.186 In contrast, 2-bromo-l-phenylpropane gives only a 43% yield of 1-phenylpropane the remainder consists of Friedel-Crafts alkylation products.186 Some alkyl halides resist reduction by this method, even when forcing conditions are employed. These include p-nitrobenzyl bromide, 3-bromopropanenitrile, and 5-bromopentanenitrile.186... 

Reductive 1,3-elimination reaction of alkyl dihalides constitutes one of the classical methods for the preparation of cyclopropyl derivatives and is particularly useful for the synthesis of highly strained polycyclic hydrocarbons. A new preparation method of [l.l.ljpropellane, more versatile than the original Wiberg s method, has been devised3,4. Thus, treatment of l,l-dibromo-2,2-bis(chloromethyl)cyclopropane with alkyllithium or lithium powder affords [1.1. ljpropellane by two successive 1,3-eliminations of halogens by way of 1 -bromo-2-(chloromethyl)bicyclo[l. 1. Ojbutane (equation 1). This method has been... 

Decyanation.1 Alkyl nitriles can be reductively decyanated to hydrocarbons by treatment with iron(III) acetylacetonate and sodium sand under argon in dry benzene... 

Where the nature of the metal or experimental conditions render such auxiliary complexation with either the substrate or the solvent less favorable, there is an increased tendency towards homolysis of the carbon-metal bond. Treatment of organolithium and organomagnesium alkyls with transition metal halides leads to metal halide reduction and hydrocarbon, suggestive of the transitory formation of metal alkyls (45), decomposing thereupon into a lower salt and free alkyl radicals ... 

Reduction in the alditol series results in conversion to deoxy derivatives or hydrocarbons, for the only groups present are alcoholic hydroxyls. The reduction of alditols to secondary alkyl iodides by treatment with hydriodic acid according to the method of Erlenmeyer and Wanklyn 114) is mainly of historical interest. 

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