Hydrochloric Acid → N-[(R)-1-ethoxycarbonyl-2-heptylthioethyl]-alanyl-(S)-prolyl-(S)-proline t-butyl ester

Participants

Reaction Steps

In 25 ml of DMF were dissolved 2.6 g of the β-isomer of N-[(R)-1-ethoxycarbonyl-2-heptylthioethyl]-alanine prepared in Reference Example 29, 2.5 g of (S)-prolyl-(S)-proline t-butyl ester prepared in Reference Example 28, 1.7 g of WSCD.HCl and 1.1 g of HOBt. To the solution was added 3.6 ml of triethylamine while being stirred with ice cooling. The solution was stirred overnight. The reaction mixture was poured into ice water, followed by extraction with ethyl acetate. The extract was washed with a saturated aqueous solution of sodium hydrogencarbonate and then with a saturated aqueous solution of sodium chloride and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (a 30:1 mixture of chloroform and methanol as an eluent), giving the title compound as a colorless oil. Yield 3.5 g.

Provenance & Evidence