Dicyclohexylcarbodiimide → Tyrosine Methyl Ester

Participants

Reaction Steps

To a stirred solution of L-tyrosine methyl ester hydrochloride (5.84 g, 25.3 mmol) and N-[(1,1-dimethylethoxy)carbonyl]amino]-cyclopentanecarboxylic acid (5.80 g, 25.3 mmol) in dichloromethane (100 mL) and triethylamine (3.52 mL, 25.3 retool) is added 1,3-dicyclohexylcarbodiimide (5.22 g, 25.3 retool) and 1-hydroxybenzotriazole (3.42 g, 25.3 mmol). The mixture is stirred for 16 hours and then the solid precipitate is filtered away. The organic phase is washed with a saturated solution of sodium bicarbonate (30 mL), brine, dried over MgSO4, filtered and concentrated under reduced pressure to give a white foam. The foam is purified by flash chromatography on silica gel, eluting with hexane-ethyl acetate (1:1). The pure fractions are concentrated and the resulting foam is crystallized from ethyl acetate-hexane to afford N-[[(1,1-dimethylethoxy)carbonyl]-amino]-1-cyclopentyl]carbonyl]-L-tyrosine methyl ester, m.p. 170°-171° C., [α]D =+6.45 (methanol, c 7.41 ).

Provenance & Evidence