Acetic Acid → H-D-Trp-D-Phe-OMe

Participants

Reaction Steps

A mixture of Z-D-Trp-D-Phe-Ome (2.00 g, 4.0 mmoles, described in Example 6) and 5% Pd/C (0.25 g) in acetic acid is stirred rapidly under an atmosphere of hydrogen. After completion of hydrogen uptake a stream of nitrogen is passed through the mixture for 15 min, the catalyst is removed by filtration, and the acetic acid is removed under reduced pressure. The residue is taken into benzene, evaporated under reduced pressure (twice), and dried under reduced pressure over KOH pellets to give H-D-Trp-D-Phe-OMe.CH3CO2H. The above product is dissolved in dry DMF (20 ml) and cooled to 0° C. N-ethylmorpholine (0.512 ml, 4 mmoles) is added, followed by ##STR97## (2.00 g, 4 mmoles). The solution is stirred at 0° C for 30 min and for 3 days at room temperature. The solvent is evaporated under reduced pressure, the residue is taken into EtOAc and washed with cold saturated NaHCO3 solution, water, cold citric acid (2N), water, saturated NaHCO3 solution and saturated NaCl solution. The EtOAc solution is dried with MgSO4 and evaporated under reduced pressure to afford the crude title product. After chromatography on a column of silica gel (300 g) with CHCl3 containing MeOH (5%) and pyridine (0.1%) as eluent, the chromatographically pure product is triturated with ether, filtered, dried under reduced pressure, and crystallized from MeOH-CH2Cl2 -isopropyl ether to give the title compound; mp 172° - 174° C, [α]D25 = +18.9° (c = 1, DMF).

Provenance & Evidence