Use of α-2-cyanoethyl tert-butoxycarbonylaspartate as an intermediate for synthesis of β-esters

The use of α-2-cyanoethyl Boc-aspartate is proposed for the first time for the synthesis of β-esters of Boc-aspartic acid. The α-2-cyanoethyl protective group is selectively split out by strong organic bases under hydrolytic conditions without the β-ester bond being affected. Using the α-2-cyanoethyl derivative, β-cyclohexyl, β-benzyl, and β-tert-butyl Boc-aspartates have been synthesized in good yields.