Reduction of nitriles to amines

R4N= BnEtsN or BU4N Heterocylces 1980, 14, 1437, 1441 reduction of amides to amines reduction of nitriles to amines... 

REDUCTION WITH ALANE (ALUMINUM HYDRIDE) IN SITU Reduction of Nitriles to Amines [787]... 

Lithium aluminium hydride has also been used for the reduction of nitriles to amines a recommended procedure involves the slow addition of the nitrile to at least one molar proportion of the reducing agent in a cooled ethereal solution.205 The reduction of nitriles is also effected by the use of sodium trifluoro-acetoxyborohydride (from sodium borohydride and trifluoroacetic acid) in tetrahydrofuran solution.206... 

Co2B in combination with i-BuNH BH3 is a new, superior reagent for selective reduction of nitriles to amines in 75-90% yield. It does not reduce a,/ -unsaturated esters to any extent and reduces alkenes and alkynes only slowly. 

Other reductions. A mixed hydride of ratio 1 1 is superior to lithium aluminum hydride alone for the reduction of nitriles to amines. Unlike lithium aluminum hydride, the mixed reagent does not reduce nitro groups. Thus p-nitrobenzaldehyde is reduced by mixed hydride to p-nitrobenzyl alcohol in 75% yield. Whereas lithium aluminum hydride tends to remove halogen atoms, this reduction is retarded or prevented by the presence of aluminum chloride. Thus (8-bromopropionyl chloride is reduced by a 1 1 mixed hydride to 3-bromo-1-propanol in 77% yield in the absence of AlClj the yield is 44%. ... 

The reduction of nitriles to amines can be carried out by LAH or SAH in an ether medium, LAH-N-methylpyrrolidine complex, AIH3 in Et20 or AlH3-Et3N [BK5, CBS, CB7, E2, FSl, H3, L2, M3, MCI, MP2, PSl]. Li(MeO)3AlH or Red-Al at 80°C reduces aromatic nitriles, while aliphatic nitriles remain untouched [M3]. This transformation can also be accomplished with BH3 THF or aminoboranes under... 

The precipitate of nickel obtained on adding zinc dust to a solution of nickel chloride can be activated by treatment with aqueous ammonia (Urushibara Ni—NH3). This nickel catalyst contains appreciable amounts of residual ammonia and is suitable for reduction of nitriles to amines. Treating the nickel precipitate with sodium hydroxide solution gives the Urushibara Ni—B catalyst Urushibara Co—B catalyst is obtained analogously from cobalt chloride.180... 

The hydrogenation of functionalities in the carboxylic acid oxidation state can also be useful for small- or large-scale syntheses. For example, the hydrogenation of adiponitrile generates hexamethylenediamine that is one of the two monomers in the production of nylon. This reaction is conducted with a heterogeneous catalyst, but homogeneous catalysts for the reduction of nitriles to amines would be convenient for the conversion of nitriles to amines on a laboratory scale. The hydrogenation of esters to aldehydes would... 

This chapter describes newly discovered reactions and synthetic utilities of lithium aminoborohydrides (LABs) including (1) the reduction of nitriles to amines, (2) the direct synthesis of amine-borane complexes from LABs and benzylic or alkyl halides (nitrogen transfer), and (3) the tandem nitrogen transfer/reduction of halogen-substituted benzonit-riles to give the corresponding aminobenzylamines. 

Heated nickel can also be used in the laboratory to catalyse the reduction of nitriles to amines using hydrogen gas. The Haber and Contact processes are both examples of chemical equilibria (Chapter 7) and the resulting mixtures will contain both reactants and products. 

Amides may also be prepared by reduction of nitriles to amines followed by acylation. See section 103 (Amines from Nitriles)... 

Reactions.— Nitriles can be reduced to aldehydes in aqueous media by photochemically generated hydrated electrons. The reduction of nitriles to amines by sodium borohydride is catalysed by Raney nickel. The transition metal promoted reductive decyanation of alkyl nitriles to homologous hydrocarbons with one less carbon atom is reported, and has been shown by van Tamelen to proceed by a different mechanism from that of a similar reduction by alkali metals in ammonia, where a process of stepwise two-electron transfer has been proposed. In the former reaction, where use is made of ferric acetylacetonate and sodium, the proton required for alkane production is derived exclusively from the acetylacetonate ligand, alkane being formed before a proton source is added this suggests a mechanism which involves initial co-ordination of the nitrile to iron, followed by reductive cleavage of the nitrile 1,2-carbon bond and proton transfer to this area, as pictured in Scheme 42. 

Figure 1.7 Selected biocatalytic reductions of nitriles to amines [101],...

The initial impetus to and the principles of the divergent mode of synthesis of arborescent molecules can be historically traced to a 1978 article by Vogtle [4], who first defined the concept of cascade process. He showed how to proliferate amine functions upon starting from benzylamine and repeating a sequence of two reactions the Michael addition and the reduction of nitriles to amines. Vogtle had to stop at rather an early stage while attempting to synthesize his polyamine dendrimers because of the lack of selectivity of the Michael reaction. 

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