Alkylation of amine-alkyl(C-allcoxy-N-ethylcyano)borane with Et(3)OBF(4) resulted in the isolation of amine-alkyl(C-alkoxy-N,N-diethyrcyano)borane tetrafluoroborates, which, upon aqueous base hydrolysis, yielded both the amine-alkyl(C-alkoxycarbonyl)borane and the amine-alkyl(N,N-diethylcarbamoyl)borane in varyng ratios. Amine-alkyl(C-alkoxycarbonyl)boranes (amine = quinuclidine, pyridine; alkyl = iBu, iPr, sBu; alkoxy R = Me, benzyl) representative of several amino acid analogues have been isolated and characterized. These are the first ester derivatives of a boron analog other than glycine.