Scheme 1.

Enzymatic syntheses of LacdiNAc standard (5) and of functionalized disaccharides 6 and 7. LacdiNAc (5) was prepared from donor 1 and GlcNAc (2) under the catalysis by Tyr470His mutant of the β-N-acetylhexosaminidase from Talaromyces flavus in (i), McIlvaine buffer pH 5.0/acetonitrile, 9/1, v/v, 45 °C, 4 h; disaccharide 6 was prepared from donor 1 and acceptor 3 under the catalysis by Tyr470His mutant of the β-N-acetylhexosaminidase from Talaromyces flavus in (ii), McIlvaine buffer pH 5.0/acetonitrile, 9/1, v/v, 45 °C, 5 h; disaccharide 7 was prepared from donor 1 and acceptor 4 using the same enzyme in (iii), McIlvaine buffer pH 5.0/acetonitrile, 9/1, v/v, 45 °C, 6.5 h