Borane complexes as novel reducing agents

The hydroboration of alkenes with borane complexed to hindered tertiary amines was studied. Complexes capable of hydroboration at room temperature were too active to manipulate in the open atmosphere. The more stable complexes could not hydroborate alkenes at room temperature. In refluxing ethereal solvents, in the presence of methyliodide, strongly complexed borane-amines hydroborated alkenes completely. The successful hydroboration of simple alkenes with borane-triphenylphospbite was achieved in refluxing ethereall solvents in the presence of methyl iodide or benryliodide, or in the presence of sulphur. Rorane-triphenylphosphito hydroboratedalkenes in refluxing ethereal solvents with no activation. The triphenylphosphine and triphenylphosphite complexes of thexylborane were studied as hydroborating agents. They behaved in a manner very similar to thexylborane-triethylamino. The use of borane-pyridine as a reducing agent for the reductive amination of aldehydes and ketones with primary aromatic and aliphatic amines was studied. Results were encouraging, suggesting that borane-pyridine in acidic media could be developed into a useful practical reagent for this reaction.