반응 #90565

반응 방정식

I2

210

Allyl 3,4-di-O-benzyl-2-O-levulinoyl-α-L-rhamnopyranoside

→

hemiacetal

수율 94.2%

3,4-Di-O-benzyl-2-O-levulinoyl-α-L-rhamnopyranose

수율 94.2%

용매

THF H2O

THF

THF

반응 조건

후처리

1. 1
   기타the resulting red solution was degassed in an argon stream
2. 2
   기타Hydrogen was then bubbled through the solution
3. 3
   기타The solution was then degassed again in an argon stream
4. 4
   workup.ADDITIONadded
5. 5
   농축concentrated to dryness
6. 6
   workup.STIRRINGThe mixture was stirred at rt for 1 h
7. 7
   기타THF was evaporated
8. 8
   세척washed twice with water
9. 9
   기타The organic layer was dried
10. 10
    농축concentrated
11. 11
    세척The residue was eluted from a column of silica gel with 7:3 to 6:4 Cyclohexane-EtOAc

실험 절차

1,5-Cyclooctadiene-bis(methyldiphenylphosphine)iridium hexafluorophosphate (25 mg, 20 μmol) was dissolved THF and the resulting red solution was degassed in an argon stream. Hydrogen was then bubbled through the solution, causing the colour to change to yellow. The solution was then degassed again in an argon stream. A solution of 210(1.4 g, 3.12 mmol) in THF was degassed and added. The mixture was stirred at rt overnight, then concentrated to dryness. The residue was dissolved in a solution of I2 (1.37 g, 5.4 mmol) in 30 mL of THF/H2O (15:4). The mixture was stirred at rt for 1 h, and THF was evaporated. The resulting suspension was taken up in DCM, washed twice with water, satd aq NaHSO3, water, satd aq NaHCO3, water and said aq NaCl, successively. The organic layer was dried and concentrated. The residue was eluted from a column of silica gel with 7:3 to 6:4 Cyclohexane-EtOAc to give the corresponding hemiacetal 211 (1.3 g, 93%). 1H NMR: δ 7.40-7.30 (m, 10H, Ph), 5.40 (dq, 1H, J1,2=1.8, J2,3=3.4 Hz, H-2), 4.93 (d, 1H, J=10.8 Hz, CH2Ph), 4.78 (d, 1H, J1,2=16 Hz, H-1), 4.78 (d, 1H, J=11.2 Hz, CH2Ph), 4.63 (d, 1H, CH2Ph), 4.51 (d, 1H, CH2Ph), 3.99 (m, 1H, J3,4=9.5 Hz, H-3), 3.78 (dq, 1H, J4,5=9.5, J5,6=6.2 Hz, H-5), 3.43 (pt, 1H, H-4), 2.80 (m, 4H, Lev), 2.19 (s, 3H, Ac), 1.37 (d, 3H, H-6). Anal. Calcd for C28H34O7: C, 67.86; H, 6.83. Found: C. 67.94; H, 6.87.

출처