2,4,6-Tris(1-methylethyl)benzenesulfonyl chloride → 5-Acetylamino-7-(2,4,6-triisopropyl-benzenesulfonyloxy)-3-(2,3,5-tri-o-acetyl-beta-d-ribofuranosyl)thiazolo[4,5-d]pyrimidin-2-one

Participants

Reaction Steps

The intermediate from Step 1 above (500 mg, 0.98 mmol) was dissolved in DCM (15 mL) at ambient temperature. DMAP (7.3 mg, 0.06 mmol), and TEA (16 ml, 11 mmol) were added to the solution, followed by 2,4,6-triisopropylbenzenesulfonyl chloride (454 mg, 1.5 mmol). After 1 h the reaction had gone to completion, the crude mixture was concentrated, and then purified by flash chromatography (SiO2, 10% EtOAc—CHCl3), affording 690 mg (92%) of 5-acetylamino-7-(2,4,6-triisopropyl-benzenesulfonyloxy)-3-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)thiazolo[4,5-d ]pyrimidin-2-one as a foaming white solid 17: 74.5-76.3° C.; Rf=0.7 (SiO2, 20% EtOAc—CHCl3); 1H (400 MHz, d6-DMSO) δ 10.83 (s, 1H), 7.39 (s, 2H), 6.03 (d, J=4.0, 1H), 5.91-5.96 (m, 1H), 5.69 (t, J=6.4, 1H), 4.30-4.70 (m, 1H), 4.22-4.26 (m, 1H), 4.16-4.20 (m, 1H), 3.90-4.00 (m, 2H), 2.97-3.01 (m, 1H), 2.07 (s, 3H), (s, 3H), 2.04 (s, 3H), 1.88 (s, 3H), 1.17-1.25 (m, 18H).

Provenance & Evidence