Hydrochloric Acid → (-)-Asparagine

Participants

Reaction Steps

HA-Asn was synthesized as follows. L-asparagine methyl ester hydrochloride (Bachem) was added to an anhydrous DMSO solution (5 mg/mL) of HA-TBA synthesized using HA-Na (99 kDa) as a starting material in Example 1-2 in an amount of 5 molar equivalents relative to the HA unit. Next, DMT-MM was added in an amount of 3-6 molar equivalents relative to the HA unit, and stirring was performed at room temperature overnight. After the reaction solution was reprecipitated with diethyl ether and the precipitate was dissolved in ultrapure water, 5N NaOH solution was added to adjust the pH to at least 12.5, and stirring was performed for an hour to perform carboxy deprotection via ethyl ester hydrolysis. Thereafter, the mixture was neutralized with 5N HCl solution and further dialyzed for purification against an aqueous solution of 0.3 M NaCl, distilled water, and ultrapure water in this order, and then the dialyzate was freeze-dried to give HA-Asn as a white solid.

Provenance & Evidence