Reaction SMILES: [CH:1]1[C:7](=[O:8])[NH:6][C:4](=[O:5])[N:3]([C@@H:9]2[O:13][C@H:12]([CH2:14][O:15][P:16]([O:19][P:20]([OH:23])([OH:22])=[O:21])([OH:18])=[O:17])[C@@H:11]([OH:24])[C@H:10]2[OH:25])[CH:2]=1.OC1O[C@H](CO)[C@@H](O)[C@H](O)[C@H]1NS(O)(=O)=O.OC1O[C@H](CO)[C@@H](O)[C@H](O)[C@H]1NS(O)(=O)=O.C1C(=O)NC(=O)N([C@@H]2O[C@H](COP(OP(O)(O)=O)(O)=O)[C@@H](O)[C@H]2O)C=1.O[CH:84]1[O:91][C@H:90]([CH2:92][O:93]N=[N+]=[N-])[C@@H:88]([OH:89])[C@H:86]([OH:87])[C@H:85]1[NH:97][C:98]([CH3:100])=[O:99]>[OH-].[Na+]>[CH3:100][C:98]([NH:97][C@H:85]1[C@@H:84]([O:21][P:20]([O:19][P:16]([O:15][CH2:14][C@H:12]2[O:13][C@@H:9]([N:3]3[C:4](=[O:5])[NH:6][C:7](=[O:8])[CH:1]=[CH:2]3)[C@H:10]([OH:25])[C@@H:11]2[OH:24])([OH:18])=[O:17])([OH:22])=[O:23])[O:91][C@H:90]([CH2:92][OH:93])[C@@H:88]([OH:89])[C@@H:86]1[OH:87])=[O:99]
Reactant: O=c1ccn([C@@H]2O[C@H](COP(=O)(O)OP(=O)(O)O)[C@@H](O)[C@H]2O)c(=O)[nH]1
Reactant: CC(=O)N[C@H]1C(O)O[C@H](CON=[N+]=[N-])[C@@H](O)[C@@H]1O
Agent: O=S(=O)(O)N[C@H]1C(O)O[C@H](CO)[C@@H](O)[C@@H]1O
Agent: [Na+]
Agent: [OH-]
Product: CC(=O)N[C@H]1[C@@H](OP(=O)(O)OP(=O)(O)OC[C@H]2O[C@@H](n3ccc(=O)[nH]c3=O)[C@H](O)[C@@H]2O)O[C@H](CO)[C@@H](O)[C@@H]1O
Yield: 98 %

Procedure:
The N-TFA group in UDP-GlcNTFA (T5b-10) as well as the N3 group in UDP-GlcN3 (T5b-11) UDP-GlcNAc6N3 (T5b-12), and UDP-GlcN36S (T5b-15) can be easily converted to a free amine, allowing further modifications to generate a diverse array of N-substituted UDP-GlcNAc derivatives. As shown in FIG. 5A, the N-TFA group at C2 of UDP-GlcNTFA T5b-10 (or F5-1) was removed under mild basic condition to produce UDP-glucosamine (UDP-GlcNH2, F5-2) in 98% yield. Selective acylation of the free amine group in F5-2 using various acyl chlorides produced C-2 modified UDP-GlcNAc derivatives UDP-N-acetoxyacetylglucosamine (UDP-GlcNGcAc, F5-4), UDP-N-azidoacetylglucosamine (UDP-GlcNAz, F5-6), UDP-N-phenylacetylglucosamine (UDP-GlcNPh, F5-7), and UDP-N-(1,1′-biphenyl-4-yl)acetylglucosamine (UDP-GlcNPh2, F5-8) in 68-95% yields. Deacetylation of compound F5-4 using catalytic amount of NaOMe in MeOH provided UDP-N-hydroxyacetylglucosamine (UDP-GlcNGc, F5-5) in 98% yield. In addition, although UDP-GlcNS T5b-16 (or F5-3) was unable to be prepared from GlcNS (T5b-8) (Table 5b) in the one-pot three-enzyme system, it was readily obtained by N-sulfation of compound F5-2 with Py.SO3 in 2 M of NaOH aqueous solution in a very good yield (86%) (FIG. 5A). Similarly as shown in FIG. 5B, catalytic hydrogenation of the azido group at the C-6 of UDP-GlcNAc6N3 T5b-12 (or F5-9) generated UDP-6-amino-6-deoxyl-N-acetylglucosamine (UDP-GlcNAc6NH2, F5-10) with an excellent yield (96%). Selective acylation of the free amino group of F5-10 using various acyl chlorides produced C-6 modified UDP-GlcNAc derivatives including UDP-6-acetoxyacetamido-N-acetylglucosamine (UDP-GlcNAc6NGcAc, F5-11), UDP-6-azidoacetamido-N-acetylglucosamine (UDP-GlcNAc6NAz, F5-13), UDP-6-phenylacetamido-N-acetylglucosamine (UDP-GlcNAc6NPh, F5-14), and UDP-N-(1,1′-biphenyl-4-yl)acetamido-N-acetylglucosamine (UDP-GlcNAc6NPh2, F5-15) in 61-91% yields. Finally, C-6 modified derivative UDP-N-hydroxyacetamido-N-acetylglucosamine (UDP-GlcNAc6NGc, F5-12) was obtained in 98% yield by treating compound F5-11 in NaOMe and methanol.