Cyanomethyl 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-galactopyranoside

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-S-(2,3,4,6-Tetra-O-acetyl-β-D-galactopyranosyl)-2-thiouronium bromide (7; 16.11 g, 31.07 mmol), sodium metabisulphite (11.81 g, 62.14 mmol), potassium carbonate (4.72 g, 34.18 mmol), and chloroacetonitrile (8.21 g, 108.7 mmol) were dissolved in acetone/water (50:50 v/v, 200 mL), and stirred for 1 hour at room temperature. The reaction mixture was poured in ice-water (300 mL), and stirred for an additional 2 hours. The white precipitate was collected by filtration and recrystallized from hot methanol (30 mL). The product was filtered off as a white crystalline solid (9.61 g, 77%). M.p.=97° C. (Lit: 95-97° C.). 1H-NMR (400 MHz, CDCl3): δ=2.00 (s, 3H, CH3), 2.07 (s, 3H, CH3), 2.09 (s, 3H, CH3), 2.17 (s, 3H, CH3), 3.35 (d, J=17 Hz, 1H, S—CH), 3.64 (d, J=17 Hz, 1H, S—CH′), 4.01 (t, J=6.9 Hz, 1H, H5), 4.16 (m, 2H, H6, H6′), 4.7 (d, J1,2=10 Hz, 1H, H1), 5.11 (dd, J3,4=3.2 Hz, J2,3=10 Hz, 1H, H3), 5.24 (t, J=10 Hz, 1H, H2), 5.47 (d, J=2.4 Hz, 1H, H4). FT-IR (ATR): ν=2249 (CN, w), 1739 (C═O, s). stirred for an additional 2 hours The white precipitate was collected by filtration recrystallized from hot methanol (30 mL) The product was filtered off as a white crystalline solid (9.61 g, 77%) M.p.=97° C. (Lit: 95-97° C.)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The galactose coupling agent 2-imino-2-methoxyethyl-1-thio-β-D-galactopyranoside (9) was prepared starting from 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide (6) in 3 steps via the intermediates 2-S-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-2-thiouronium bromide (7) and cyanomethyl 2,3,4,6-tetra-O-acetyl-1-thio-β-D-galactopyranoside (8) as shown in FIG. 5.