In our pursuit of an efficient, protecting-group-free synthesis of the dual CCK1/CCK2 receptor antagonist 1, we have developed chemoselective conditions for sulfonamide formation reaction in pure water and a PhNMe2 mediated carboxamide formation, both in the presence of a carboxylic acid. Practical synthesis of an unnatural, chiral β-aryl-α-amino acid is also described.
