反应详情

For the reaction by the active ester process, 4.26 g. (0.02 mol) N-(furyl-(2')-methoxycarbonyl)-L-alanine and 5.4 g. (0.04 mol) N-hydroxybenzotriazole are dissolved in 50 ml. anhydrous tetrahydrofuran (THF), cooled to 0° C. and mixed with a solution of 4.4 g. (0.022 mol) dicyclohexylcarbodiimide (DCC) in 10 ml. anhydrous THF. For the formation of the active ester, the reaction mixture is stirred for 1.5 hours at 0° C. and then for 2 hours at ambient temperature. Thereafter, with the exclusion of oxygen and water, there are added thereto 2.66 g. (0.02 mol) indoxyl and 2.77 ml. (0.04 mol) anhydrous triethylamine. The reaction mixture is stirred for 18 hours at ambient temperature. The N,N'-dicyclohexylurea formed is filtered off with suction, the solvent is distilled off in a vacuum and the residue is worked up in the manner described in Example 7. The amorphous crude product obtained is then purified by column chromatography on a silica gel column with a mixture of toluene and ethyl acetate (5:1 v/v). After evaporation of the appropriate collected fractions and recrystallization of the residue from ethyl acetate-petroleum ether (1:1 v/v), there are obtained 3.0 g. (45.7% of theory) 3-[N-(furyl-(2')-methoxycarbonyl)-L-alanyloxy]-indole in the form of colorless crystals; m.p. 129° C.: [α]D20 =-51.9° (c=1% in methanol).

1. additionmixed with a solution of 4.4 g