Reacción #90570

Ecuación de reacción

hemiacetal

(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-(1→2)-3,4-di-O-benzyl-α-L-rhamnopyranose

Trichloroacetonitrile

DBU

→

307

Rendimiento 86.0%

(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-(1→2)-3,4-di-O-benzyl-α-L-rhamnopyranose trichloroacetimidate

Rendimiento 86.0%

Disolventes

CH2Cl2

Condiciones de reacción

Tratamiento posterior

1. 1
   ConcentraciónThe mixture was concentrated
2. 2
   LavadoThe residue was eluted from a column of silica gel with 1:1 cyclohexane-EtOAc and 0.2% of Et3N

Procedimiento

The hemiacetal 320 (541 mg, 0.80 mmol) was dissolved in CH2Cl2 (20 mL), placed under argon and cooled to 0° C. Trichloroacetonitrile (0.810 mL, 8 mmol), then DBU (10 μL, 80 μmol) were added. The mixture was stirred at 0° C. for 1 h. The mixture was concentrated and toluene was co-evaporated from the residue. The residue was eluted from a column of silica gel with 1:1 cyclohexane-EtOAc and 0.2% of Et3N to give 307 (560 mg, 86%) as a colourless foam; [α]D+2° (c 1, CHCl3). 1H NMR: δ 8.56 (s, 1H, NH), 7.50-7.20 (m, 10H, Ph), 6.29 (d, 1H, J1,2=1.3 Hz, H-1A), 5.50 (d, 1H, J2,NH=8.3 Hz, NHD), 5.17 (pt, 1H, J2,3=J3,4=9.5 Hz, H-3D), 5.09 (dd, 1H, J4,5=9.5 Hz, H-4D), 4.85-4.60 (m, 4H, CH2Ph), 4.68 (d, 1H, J1,2=8.0 Hz, H-1D), 4.22-4.10 (m, 2H, J5,6=5.0, J6a,6b=12.2 Hz, H-6aD, 6bD), 4.00 (m, 1H, H-2D), 3.99 (dd, 1H, J2,3=3.5 Hz, H-2A), 3.90 (dq, 1H, J4,5=9.6, J5,6=6.2 Hz, H-5A), 3.89 (dd, 1H, J3,4=9.5 Hz, H-3A), 3.62 (m, 1H, H-5D), 3.50 (dd, 1H, H-4A), 2.02, 2.00, 1.98 (3s, 9H, OAc), 1.65 (s, 3H, NHAc), 1.32 (d, 3H, H-6A); 13C NMR: δ 171.2, 171.0, 170.4, 169.6 (C═O), 160.5 (C═NH), 138.2-128.0 (Ph), 103.3 (C-1D), 97.3 (C-1A), 91.4 (CCl3), 80.3 (C-4A), 79.9 (C-3A), 77.5 (C-2A), 76.0, 73.8 (2C, CH2Ph), 73.1 (C-3D), 72.2 (C-5D), 71.1 (C-5A), 68.8 (C-4D), 62.5 (C-6D), 54.8 (C-2D), 23.3 (NHAc), 21.4, 21.1, 21.0 (3C, OAc), 18.4 (C-6A) Anal. Calcd for C36H43Cl3N2O13: C, 52.85; H, 5.30; N, 3.42. Found: C, 52.85; H, 5.22; N, 3.47.

Fuente