Triethylamine → L-asparagine, N-[1-(2-adamantan-1-yl-2-oxoethyl)-L-prolyl] benzylamide

Using the procedure described previously, a heterogeneous solution of 1-(2-adamantan-1-yl-2-oxoethyl) L-proline (152 mg, 0.52 mmol, 1.0 eq), L-asparagine N-benzylamide (231 mg, 1.04 mmol, 2.0 eq) and dichloromethane (1.5 mL), was treated with triethylamine (436 uL, 3.1 mmol, 6.0 eq), and a 50% solution of 1-n-propylphosphonic acid cyclic anhydride in dichloromethane (663 uL, 1.04 mL, 2.0 eq), to provide 130.7 mg (51%) of L-asparagine, N-[1-(2-adamantan-1-yl-2-oxoethyl)-L-prolyl] benzylamide as a white foam.