Reaction #1994272

Reaction equation

( 2 )

5′-O-(tert-butyidimethylsilyl)-5-[3-(2,2,2-trifluoroacetamido)-prop-1-ynyl]-2′-deoxyuridine

acetic acid

acetic anhydride

DMSO

→

oil

Yield 89.0%

5′-O-(tert-Butydimethylsilyl)-3′-O-methylthiomethyl-5-[3-(2,2,2-trifluoroacetamido)-prop-1-ynyl]-2′-deoxyuridine

Yield 89.0%

Conditions

Workup

1. 1
   Otherwas quenched with sat. aq. NaHCO3
2. 2
   workup.ADDITIONEtOAc (50 ml) was added
3. 3
   Extractionthe aqueous layer was extracted three times with ethyl acetate
4. 4
   WashThe combined organic layers were washed with sat. aq. NaHCO3 solution
5. 5
   Dryingdried (MgSO4)
6. 6
   OtherAfter removing the solvent under reduced pressure
7. 7
   Otherthe product (3) was purified by chromatography on silica (EtOAc: petroleum ether 8:2)

Procedure

To a solution of (2) (1.84 g, 3.7 mmol) in dry DMSO (7 ml) was added acetic acid (3.2 ml) and acetic anhydride (10.2 ml). The mixture was stirred for 2 days at room temperature, before it was quenched with sat. aq. NaHCO3. EtOAc (50 ml) was added and the aqueous layer was extracted three times with ethyl acetate. The combined organic layers were washed with sat. aq. NaHCO3 solution and dried (MgSO4). After removing the solvent under reduced pressure, the product (3) was purified by chromatography on silica (EtOAc: petroleum ether 8:2) yielding a clear sticky oil (1.83 g, 89%). 1H NMR (d6 DMSO): δ 0.00 (s, 6H, CH3), 0.79 (s, 9H, tBu), 1.96-2.06 (m, 1H, H-2′), 1.99 (s, 3H, SCH3), 2.20-2.26 (m, 1H, H-2′), 3.63-3.74 (m, 2H, H-5′), 3.92-3.95 (m, 1H, H-4′), 4.11-4.13 (m, 2H, CH2), 4.28-4.30 (m, 1H, H-3′), 4.59 (br s, 2H, CH2), 5.97 (t, J=6.9 Hz, 1H, H-1′), 7.85 (s, 1H, H-6), 9.95 (t, J=5.3 Hz, 1H, NH), 11.64 (s, 1H, NH). Mass (−ve electrospray) calcd for C22H32F3N3O6SSi 551.17. Found 550.

Source