Aldehyde from alcohols

Vinyllithium [917-57-7] can be formed direcdy from vinyl chloride by means of a lithium [7439-93-2] dispersion containing 2 wt % sodium [7440-23-5] at 0—10°C. This compound is a reactive intermediate for the formation of vinyl alcohols from aldehydes, vinyl ketones from organic acids, vinyl sulfides from disulfides, and monosubstituted alkenes from organic halides. It can also be converted to vinylcopper [37616-22-1] or divinylcopper lithium [22903-99-7], which can then be used to introduce a vinyl group stereoselectively into a variety of a, P-unsaturated systems (26), or simply add a vinyl group to other a, P-unsaturated compounds to give y, 5-unsaturated compounds. Vinyllithium reagents can also be converted to secondary alcohols with trialkylb o r ane s. 

An extension of this method can be used to prepare allylic alcohols. Instead of being protonated, the (3-oxido ylide is allowed to react with formaldehyde. The (J-oxido ylide and formaldehyde react to give, on warming, an allylic alcohol. Entry 12 is an example of this reaction. The reaction is valuable for the stereoselective synthesis of Z-allylic alcohols from aldehydes.245... 

The formation of mercaptan is doubly important because of its relation to phytochemical reduction processes. The reaction is analogous to the formation of ordinary alcohols from aldehydes and it also indicates how the plant is capable of synthesizing intensely odorous substances from aldehydes and hydrogen sulfide in a simple manner. The isolation... 

Reduction of carbonyl compounds with metal hydrides or boranes a. primary alcohols from aldehydes, acids, acid halides, and esters... 

On the other hand, the production of desired compounds through reduction of starting material requires the electron donors to be oxidized (reductant). Alcohols are often used not only as a solvent but as the donor to produce useful compounds, e.g., anilines from nitrobenzenes,22) alcohols from aldehydes,23) and secondary amines from the corresponding Schiff bases.24) From the organic synthetic point of view, however, the separation of undesired products, aldehydes or ketones, from the alcohols is necessary unless subsequent reaction processes consume them25,26) or they are easily removed by distillation or other procedures. A recent report has shown that water acts as the electron donor and is converted into 02 in the photocatalytic regio-selective reduction of terpenes mixed with aqueous suspension of Ti02.27,28) It is notable that isolation of the desired product from the reaction mixture is simple in this type of photocatalytic reduction. 

Application of alumina-supported sodium borodeuteride under the reaction conditions described by Varma26 provided deuterated alcohols from aldehydes and ketones with a high degree of deuterium incorporation. The method is thus suitable for isotopic labelling procedures (Scheme 4.12)32. 

The metal lias to a great extent replaced zinc, which was used in 1849 by Frankland in the preparation of paraffin hydrocarbons and the zinc alkyls, and subsequently by Wagner for preparing secondary alcohol from aldehydes, by Saytzeff in preparing tertiary alcohols from ketones, and by Butlerow iu the preparation of both ketones and tertiary alcohols from acid chlorides. 

Pradhan, S.K, Tetrahedron, (1986), 42, 6351 Related Methods Alcohols from Aldehydes (Section 34)... 

Transmetalation of cinnamyl and crotyl tributyltin reagents by SnCl2 in acetonitrile has been proposed to explain the predominant formation of anti homoallylic alcohols from aldehydes (Table 23) [41]. In contrast, the syn adducts predominate when these reactions are conducted in CH2CI2. The exchange reaction in acetonitrile was confirmed by the quantitative formation of BusSnCl. Presumably the putative allylic SnCl species is stabilized by complexation with acetonitrile (Eq. 25). 

Synthetic and biological interest in highly functionalized acyclic and cyclic amines has contributed to the wealth of experimental methodology developed for the addition of carbanions to the caibon-mtrogen double bond of imines/imine derivatives (azomethines). While a variety of practical methods exist for the enantio- and stereo-selective syntheses of substituted alcohols from aldehyde and ketone precursors, related imine additions have inherent structural limitations. Nonetheless imines, by virtue of nitrogen substitution, add a synthetic dimension not available to ketones. In addition, improved procedures for the preparation and activation of imines/imine derivatives have increased the scope of the imine addition reaction. 

Sodium amalgam I rim. alcohols from aldehydes s. 2, 55 3, 32 Najig CHO CHjOH... 

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