Reaction #554620

Reaction equation

K2CO3

acetic acid

acetic anhydride

N2-isobutyryl-5′-O-(tert-butyldimethylsilyl)-2′-deoxyguanosine

DMSO

→

product 11

Yield 69.0%

N2-isobutyryl-3′-O-(methylthiomethyl)-5′-O-(tert-butyldimethylsilyl)-2′-deoxyguanosine

Yield 69.0%

Conditions

Workup

1. 1
   OtherThe crude reaction mixture
2. 2
   Extractionextracted with ethyl acetate (100×3 mL)
3. 3
   ExtractionThe combined organic extract
4. 4
   Washwas then washed with saturated NaHCO3 solution
5. 5
   Dryingdried over Na2SO4
6. 6
   Concentrationconcentrated under vacuum
7. 7
   OtherThen reaction mixture
8. 8
   Otherwas purified by a silica gel column chromatography

Procedure

5 g of N2-isobutyryl-5′-O-(tert-butyldimethylsilyl)-2′-deoxyguanosine (11.0 mmol) dissolved in 21 mL dry DMSO was treated with 10 mL acetic acid and 32 mL acetic anhydride, and stirred for 48 h at room temperature. The crude reaction mixture was then neutralized by adding a K2CO3 solution, and extracted with ethyl acetate (100×3 mL). The combined organic extract was then washed with saturated NaHCO3 solution, dried over Na2SO4 and concentrated under vacuum. Then reaction mixture was purified by a silica gel column chromatography resulting the product 11 as white powder (3.9 g, 69% yield; Rf=0.35, CH2Cl2:MeOH/20:1). HR-MS: Obs. m/z 512.2344 cald. for C22H38O5N5SiS 512.2363 [M+H]+. 1H-NMR (CDCl3): δH 12.0 (s, 1H), 8.95 (brs, 1H), 8.09 (s, 1H), 6.24 (t, J=6.8 Hz, 1H), 4.73 (m, 2H), 4.66 (m, 1H), 4.16 (m, 1H), 3.81 (m, 2H), 2.76 (m, 1H), 2.59 (m, 1H), 2.54 (m, 1H), 2.21 (s, 3H), 1.29 (m, 6H), 0.91 (s, 9H), and 0.10 (s, 6H) ppm.

Source