Novel dibasic acid salts and their synthesis

摘要

The protecting group, Z, of protected alpha-amino acid esters of the formulaPPZ--NH--CH(R.sub.2)COOCH(R)COOR.sub.1 P Pis removed in the presence of a dibasic acid such as oxalic acid. This results in the formation of a new type of salt of an amino acid ester which may be represented by the formula ##STR1## In the above Q is a divalent hydrocarbyl residue of a dibasic acid, R is a hydrogen atom or hydrocarbyl group, R.sub.1 is a hydrocarbyl group, R.sub. 2 is a hydrogen atom or hydrocarbyl group, and p is zero or one, preferably zero. When p is zero, the salts are oxalate salts. When p is one, the salts are salts of other dibasic acids. The salts (II) are useful as reactants in the synthesis of amino-acid substituted phosphazene polymers.