Chemo- and enzymatic synthesis of partially and fully N-deacetylated 4-methylumbelliferyl chitobiosides: Fluorogenic substrates for chitinase

Partially and fully N-deacetylated 4-methylumberlliferyl chitobioside (1) derivatives, such as GlcN-GlcNAc-UMB (2), GlcNAc-GlcN-UMB ( 3), and (GlcN)2-UMB (4), were synthesized using chemo- and enzymatic procedure. Fluorescent aglycon was released from the chitobiosides 1, 2 and 3 by the action of chitinase. These UMB glycosides of heterochitobiose were versatile probes for the investigation of substrate binding chitinase from various sources. Scheme 1. (1) Concd. H2SO4/Ac2O; (2) [8 and 9]; (3) chitin deacetylase ( [10]). Scheme 2. (1) (a) HCl/AcOH, quant., (b) H2O/acetone, 73%; (2) (a) (CF3CO)2O/acetone, 70%, (b) HCl/AcOH, quant.; (c) UMBONa/DMF, 44%; (3) NH3/MeOH, 80 h, 61%; (4) chitin deacetylase ([10]).