Reaction #554621

Reaction equation

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

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

diphenylcarbamoyl chloride

N,N-diisopropylethylamine

→

product 12

Yield 80.0%

N2-isobutyryl-O6-diphenylcarbamoyl-3′-O-(methylthiomethyl)-5′-O-(tert-butyldimethylsilyl)-2′-deoxyguanosine

Yield 80.0%

Solvents

pyridine

Conditions

Workup

1. 1
   OtherThe solvent was removed under high vacuum, and product
2. 2
   Otherwas then purified by silica gel column chromatography

Procedure

To 1.0 g N2-isobutyryl-3′-O-(methylthimethyl)-5′-O-(tert-butyldimethylsilyl)-2′-deoxyguanosine (11, 1.95 mmol) dissolved in 22 mL dry pyridine were added diphenylcarbamoyl chloride (0.677 g, 2.92 mmol) and 1.02 mL N,N-diisopropylethylamine, and stirred at room temperature for 3 h under nitrogen atmosphere. The reaction mixture became dark red during this time. The solvent was removed under high vacuum, and product was then purified by silica gel column chromatography using EtOAc:hex/1:1 to 7:3 as mobile phase. The product 12 was isolated as yellowish powder (1.09 g, ˜80% yield; Rf=0.7, EtOAc:hex (1:1)). HR-MS: Obs. m/z 707.3068 calcd. for C35H47O6N6SiS 707.3047 [M+H]+. 1H-NMR (CDCl3): δH 8.25 (s, 1H), 7.94 (brs, 1H), 7.47-7.37 (m, 10H), 6.42 (m, 1H), 4.75 (m, 2H), 4.71 (m, 1H), 4.18 (m, 1H), 3.88-3.70 (m, 2H), 2.80 (m, 1H), 2.60 (m, 1H), 2.19 (s, 3H), 1.30 (d, J=7.2 Hz, 6H), 0.93 (s, 9H) and 0.14 (s, 6H) ppm.

Source