Borane was generated in situ using lithium borohydride and methyl iodide in a nonpolar, non-coordinating solvent toluene, which gave marginal conversion of the nitrile to a primary amine. In order to retain generated borane in the reaction mixture through adduct formation and to minimize formation of diborane, various Lewis bases were added, including 1,4-dioxane, 1,2-dimethoxyethane, diethyl ether, triphenylphosphine, pyridine, dimethyl sulfide, tetrahy drothiophene, silica gel, alumina, 2-imidazolidone and tetrahydrofuran (THF). Less than a stoichiometric equivalent, 0.75 equivalents, of THF have been shown to be the best suited to hold borane in solution and therefore facilitate conversions of nitriles to primary amines based on yield and purity.
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amines
boron
catalysis
nitriles
protecting groups
