MannKind Corporation
Catalysis of diketopiperazine synthesis

Abstract:

Provided is a method for the synthesis of N-protected 3,6-bis-[4-aminobutyl]-2,5-diketopiperazine including the step of heating a solution of .epsilon.-amino protected lysine in the presence of a catalyst selected from the group consisting of sulfuric acid, phosphoric acid, and phosphorus pentoxide.