Gram scale production of 1-azido-β-d-glucose via enzyme catalysis for the synthesis of 1,2,3-triazole-glucosides

Abstract

The production of analytical amounts of azido sugars is used as a means of verifying catalytic acid/base mutations of retaining glycosidase, but application of this process to preparative synthesis has not been reported. The catalytic acid/base mutant of Thermoanaerobacterium xylanolyticus GH116 β-glucosidase, TxGH116D593A, catalyzed the gram scale production of 1-azido-β-d-glucose (1) from p-nitropheyl-β-d-glucopyranoside (pNPGlc) and azide via a transglucosylation reaction. Overnight reaction of the enzyme with pNPGlc and NaN₃ in aqueous MES buffer (pH 5.5) at 55 °C produced 1 (3.27 g), which was isolated as a white foamy solid in 96% yield. This 1 was successfully utilized for the synthesis of fifteen 1,2,3-triazole-β-d-glucosyl derivatives (2-16) containing a variety of functional groups, via click chemistry.

Fig. 1. Reported bioactive 1,2,3-triazole-β-d-glucosides.

Fig. 2. TLC profile of 1-azido-β-d-glucose (1) formation after 24 h from 3 mg/1 mg to 15 mg/1 mg and 5 g/370 mg of pNPGlc/enzyme (TxGH116D593A). In each case, detection under UV light is shown on the left and carbohydrate staining with 10% sulphuric acid in ethanol and charring is shown on the right. The numbers below the TLC lanes indicate ratios of pNPGlc to enzyme.

Fig. 3. Structures of alkynes (1a–o) used in click chemistry.

Fig. 4. Structures of 1,2,3-triazole-β-d-glucosyl derivatives 2–16.