Lithium aluminum hydride dehalogenation

On reduction of the chloronitrosoalkanes with hydrogen, lithium aluminum hydride, or sodium borohydride in red light, the corresponding dehalogenated ketoximes are formed [14, 52a, b]. 

DEHALOGENATION Lithium-aluminum hydride. Palladium catalysts. Sodium O.O-diethyl phosphoro te 11 uroate. Sodium dithionite. Sodium sulfide. 

Reductive dekalogenation of alkyl halides.2 Lithium aluminum hydride has commonly been used only for reductive dehalogenation of reactive substrates organotin hydrides, for example tri-n-butyltin hydride (1, 1192-1193 2, 424 3, 294), have been used for reduction of inert halides. Recently Jefford et al. have reported that supposedly inert halides are reducible by lithium aluminum hydride. Thus the vinyl halide (1) is reduced to (2, em/o-2-phenylbicyclo(3.2.1]octene-3) by lithium aluminum hydride in refluxing ether (24 hr.). 3-Bromobicyclo[3.2.1]octene-2 is reduced to the parent... 

The pteridine system is easily reduced, so that reductive dehalogenation usually results in the formation of hydropteridines. Depending on the reducing conditions, and on the starting compound, the products may be partially dehalogenated dihydro- or tetrahydropteridines. An example is the reduction of 2,4,6,7-tetrachloropteridine by four equivalents of lithium aluminum hydride to give 2,4-dichloro-5,6,7,8-tetrahydropteridine (2) in 96% yield.181... 

In contrast to the quinoline and isoquinoline series, thienopyridines are apparently resistant to reduction by tin-hydrochloric acid, since the parent systems can be obtained by reductive dehalogenation or chloro-derivatives. Quaternary salts are reduced to the JV-alkyl-4,5,6,7-tetra-hydrothienopyridine by sodium borohydride,45,48,89-91 and the azo-methine bond in dihydro derivatives (e.g. 69) is reduced by lithium aluminum hydride.47... 

DEHALOGENATION Titanium (III) chloride-Lithium aluminum hydride. Zinc. 

The transfonnations of gm-dihalocyclopropanes are synthetically useful because the cyclopropanes are readily prepared by the addition of dihalocarbene to olefins. In most of dehalogenation reactions to monohalocyclopropanes, the reagents are limited to metallic reductants such as organotin hydride, lithium aluminum hydride, sodium borohydride, Grignard reagent, and zinc-copper couple [1-9]. A versatile method for the reduction of gm-dibromocyclopropanes 3 with an organic reductant is achieved by use of diethyl phosphonate (commercially named diethyl phosphite) and triethylamine to give the monobromocyclopropanes 4 (Scheme 2.2) [10]. 

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