Temporary protection of amino groups by the group of the formula I ##EQU1## in which R.sub.1 represents lower alkyl, R.sub.2 lower alkyl or phenyl and R.sub.3 phenyl, and wherein the phenyl radicals are unsubstituted or substituted by lower alkyl, phenyl or lower alkylphenyl groups.
使用公式I ##EQU1## 中的基团暂时保护
氨基,其中R.sub.1代表较低的烷基,R.sub.2代表较低的烷基或苯基,R.sub.3代表苯基,其中苯基基团未被取代或被较低的烷基,苯基或较低的烷基苯基取代。