Halo alcohols, reaction with carbonyl

In some circumstances, the production of a 2-halo alcohol by reduction of the carbonyl group of an a-halo ketone with metal hydrides is a useful synthetic reaction ... 

With careful choice of reagent and reaction conditions, alkenes containing other functionalities can be selectively hydroxylated without complicating side reactions. For example, the oxidation may be carried out in the presence of ester, ether, sulfide, carboxylic acid, acetal, carbonyl, halo, alcohol and aryl groups. Regioselective hydroxylation is also possible in dienes in which one center is electron poor, and some selectivity is also found between isolated double bonds. For example, syn hydroxylation of diene (5) with a catalytic amount of osmium tetroxide and N-methylmorpholine N-oxide as the secondary oxidant gives diol (6) in 46% yield, and phase transfer catalyzed permanganate oxidation of diene (7) affords diol (8) in 83% yield. 

The reaction of carbonyl compounds with glycerin-a-monochlorohydrin, CHjOHCHOHCHjCl, leads to cyclic halo acetals. Treatment of a,/3-olefinic aldehydes with alcohols saturated with dry hydrogen chloride causes the addition of the halogen acid to the double bond as well as acetalization to give /3-halo acetals. ... 

When chloromethyl p-tolyl sulfoxide (102 R = p-tolyl) is treated with carbonyl compounds (103) and potassium t-butoxide in t-butyl alcohol ether, (p-tolylsulfmyl)oxiranes (104) are directly formed. Chloromethyl methyl sulfoxide (102 R = Me) exhibits the same behavior (Scheme 29). These reactions proceed with high stereoselection at the position a to the sulfmyl group. The stereochemical course proposed for the attack of the carbanion of an a-halo sulfoxide on a carbonyl compound is shown in Figure 4. ... 

Reactions of chiral allylic boranes with carbonyl compounds Reactions of chiral allyl boranes with imines Asymmetric Addition of Carbon Nucleophiles to Ketones Addition of alkyl lithiums to ketones Asymmetric epoxidation with chiral sulfur ylids Asymmetric Nucleophilic Attack by Chiral Alcohols Deracemisation of arylpropionic acids Deracemisation of a-halo acids Asymmetric Conjugate Addition of Nitrogen Nucleophiles An asymmetric synthesis of thienamycin Asymmetric Protonation... 

Secondary a-halo-ketimines are converted into a-alkylamino-acetals by reaction with anhydrous alcohols in the presence of a tertiary amine base [equation (40)]. Should the a-(alkylamino)carbonyl compound be required. 

Indium-mediated Barbier-type coupling between carbonyl compounds and allyl halides has been revealed to proceed effectively in diverse reaction media. Even under solvent-free conditions, allylation works well, although no reaction is observed with benzyl bromide and a-halo carbonyl compounds.59 Various aldehydes react with allyl bromide mediated by indium in liquid carbon dioxide to give homoallylic alcohols (Scheme 1). In contrast to the corresponding neat allylation, the liquid C02-mediated reaction can allylate solid aldehydes successfully.60 Indium-mediated allylations of carbonyl compounds with allyl bromide proceed in room temperature ionic liquids. In [bmim][BF4] and [bmim][PF6] (bmin l-butyl-3-methylimidazolium), the desired homoallylic alcohols are formed with good levels of conversion.61 Homoallyllic alcohols are also prepared by the reaction of resin-bound aldehydes (Equation (l)).62... 

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