DEPBT As Coupling Reagent to Avoid Racemization in a Solution-Phase Synthesis of a Kyotorphin Derivative

The synthesis of IbKTP-NH2 with reduction of racemization up to no detectable level has been achieved using 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT). Among all coupling systems tested, only DEPBT-mediated amide bond formation between Nα-acylated tyrosine and arginine without loss of optical purity.