Reductions with lithium in low molecular weight amines and ethylenediamine

Reductions of several types of compounds with lithium and ethylenediamine u sing low molecular weight amines as solvent are described. In all cases 1 m ol of ethylenediamine or N,N'-dimethylethylenediamine per gram-atom of lith ium was used. In some cases it was beneficial to add an alcohol as a proton donor. These reaction conditions were applied to the debenzylation of N-be nzylamide and lactams which are refractory; to hydrogenolysis with hydrogen and a catalyst. N-Benzylpilolactam 2, synthesized from pilocarpine hydroch loride in refluxing benzylamine, was debenzylated in good yield using 10 gr am-atoms of lithium per mole (10 Li/mol) of 2 in n-propylamine. The debenzy lation of N-beniyl-N-methyldecanoic acid amide, 4 (6 Li/mol), in t-butylami ne/N,N'-dimethylethylenediamine gave N-methyldecanoic acid amide 6 in 70% y ield. Alternatively, reduction of 4 (7 Li/mol) in t-butano/n-propylamine/et hylenediamine gave 12-decanal 12 in 36 % yield. Using the same conditions, thioanisole, 1-adamantane-p-toluenesulfonamide, and l-adamantane methyl-p-t oluenesulfonate were reduced with 3, 7, and 7.2 Li/mol of compound to give thiophenol (74%), adamantamine (91%), and l-adamantane methanol (75%), resp ectively. In this solvent system naphthalene and 3-methyl-2-cyclohexene-1-o ne were reduced to isotetralin (74%) and S-methyl cyclohexanone (quantitati ve) with 5 and 2.2 Li/mol of starting compound, respectively. Grimes and O- methyloximes were reduced to their corresponding amines using 5 and 8 Li/mo l of compound, respectively. Anisole was also reduced to 1-methoxy-1,4-cycl ohexadiene with 2.5 Li/mol of anisole. Undecanenitrile was reduced to undec ylamine with 8.6 Li/mol. Additionally, a base-catalyzed formation of imidaz olines from a nitrile and ethylenediamine was also explored.