An Efficient Synthesis of 2,3-Diaminoacid Derivatives Using Phosphine Catalyst

Ethyl 2,3-diphthalimidoylpropanoate was effectively synthesized from ethyl propynoate with two equivalents of phthalimide catalyzed by triphenylphosphine in good yield. The choice of reaction media was important for selective synthesis of the desired 2,3-diaminocarboxylic acid derivatives. The reaction is considered to occur through a zwitterionic intermediate derived from the reaction of the α,β-unsaturated ester with triphenylphosphine.