Nitrogen hydrides aluminum-carbon bonds

The reduction of tosylhydrazones can also be performed with sodium borodeuteride in boiling methanol or dioxane, but the mechanism of this reaction (in boiling dioxane at least) is radically different from that of the lithium aluminum deuteride reductions.82 With sodium borohydride the first step is apparently hydride attack on the carbon atom of the C=N bond which is probably concerted with the elimination of the tosylate anion (110 - 111). Migration of the hydrogen from nitrogen to C-3 in (111) concerted with expulsion of nitrogen, provides the corresponding methylene derivative (100).82... 

The carbon-nitrogen double bond in cyclic Schiff s bases can be reduced by either borohydride or aluminum hydride ions. Examples in the literature are so numerous that only a few representative examples will be mentioned to indicate the scope of the reaction. 

Treatment of an ethereal solution of 4-oxo-dihydro-l,3-diaza-anthracene (108) with lithium aluminum hydride reportedly resulted in the reduction of only the 1,2-carbon-nitrogen double bond with 4-oxo-l,2,3,4-tetrahydro-l,3-diazaanthracene (109) being the only product isolated.134 Apparently conditions were not sufficiently vigorous for the further reduction of the tautomeric form of 109, or possibly the formation of a complex with the aluminohydride pre-... 

The generation of the carbcxi-carbon double bond of unsaturated nitrogen heterocycles by the rDA reaction of cycloadducts that act as protected ethylenes has been accomplished. Azetines have been prepared by this method. Another example is the synthesis of l-methyl-3-pyrroline (201). By protecting the ethylene of N-methylmaleimide (199) with furan and then reducing with lithium aluminum hydride, adduct (200) was obtained (equation 86). Pyrolysis of adduct (200) at 250-300 C gave l-methyl-3-pyrroline (201) in 60% isolated yield. The ethylene moiety of N-substituted maleimides can also be generated via rDA reactions. Examples include the generation of N-phenylmaleimide (equation 87) and of N-acetoxymaleimide (equation 88). ... 

Addition of deuterium to carbonyl double bonds and their nitrogen analogs is accomplished by complex metal hydrides in an increasing number of examples. In this reduction two deuterium atoms are transferred of course, only the deuterium on carbon is firmly bound, and that attached to the hetero atom can be removed in the usual way. Since such reactions can in general be carried out with LiAlD4 in aprotic solvents, the use of lithium aluminum deuteride, LiAlH4,. offers no peculiarities. The necessary LiAlD4, which is extremely sensitive to hydrolysis, is commercially available. It can be conveniently handled as a solution in a dry dialkyl ether or in tetrahydrofuran at temperatures up to ca. 130°. 

Can carbon-nitrogen double and triple bonds be reduced by lithium aluminum hydride ... 

The cyanide ion is also an important synthon, but this time for [HjNCHj ] rather than ammonia. As well as adding nitrogen, the carbon chain is extended by one unit. The carbon-nitrogen triple bond can be reduced either by catalytic hydrogenation or reduction with lithium aluminum hydride (Figure 22.8). 

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