Acetic Acid → Boc-Ile-OSu

Participants

Reaction Conditions

Reaction Steps

Under stirring, 1.00 equivalent of Boc-Ile-OH.1/2 H2O (Mw=240.3) and 1.05 equivalents of Suc-OH (Mw=115) were added to ethyl acetate. The solution was cooled to 0±5° C. and then 1.10 equivalents DCC (Mw=206.3) diluted in ethyl acetate was poured into the solution. The suspension was stirred at 0° C. for at least 30 min and at room temperature for at least 5 hours. After the reaction mixture had been quenched by adding 2.4 g acetic acid (0.20 equivalents), the DCU was filtered and washed twice with ethyl acetate. The organic layers were washed with 5% (weight) aqueous NaCl solution containing 0.5 equivalents KHSO4, 5% (weight) aqueous NaCl solution; 5% (weight) aqueous NaCl solution containing 0.5 equivalents Na2CO3 and finally with 5% (weight) aqueous NaCl solution. The solvent was concentrated in vacuo. The concentrated solution was twice taken up in ethyl acetate and further evaporated in vacuo in order to eliminate the remaining water. The concentrated organic layer was diluted with cyclohexane or heptane. The precipitated suspension was stirred at room temperature for at least 30 min, filtered and finally dried under vacuum (45° C.). The dried precipitate yielded 89% (based on NMR content) of Boc-Ile-OSu as white solid.

Provenance & Evidence