反应 #2348154

反应方程式

dimethyl sulphide

dimethyl sulphide

methanesulphonic acid

podophyllotoxin

→

5-(4-hydroxy-3,5-dimethoxyphenyl)-9-hydroxy-5,8,8a,9-tetrahydro-5aH-furo[3′,4′:6,7]naphtho[2,3-d][1,3]dioxol-6-one

收率 5.7%

溶剂

trifluoroacetic acid

反应条件

后处理

1. 1
   温度is maintained for 9 hours
2. 2
   workup.STIRRINGstirring
3. 3
   温度is maintained for 9 hours
4. 4
   萃取extracted with ethyl acetate (3×300 ml)
5. 5
   洗涤The organic phases are washed with water
6. 6
   干燥After drying over sodium sulphate
7. 7
   过滤filtering
8. 8
   其他evaporating
9. 9
   其他6.3 g of crude demethylation product are obtained

实验过程

10 g (24 mmol) of podophyllotoxin are dissolved in 60 ml of trifluoroacetic acid. 5.4 ml (72 mmol) of dimethyl sulphide and 47 ml (72 mmol) of methanesulphonic acid are successively added. Stirring is maintained for 9 hours, 5.4 ml (72 mmol) of dimethyl sulphide are again added and stirring is maintained for 9 hours. The medium is run quickly onto ice (600 ml) and extracted with ethyl acetate (3×300 ml). The organic phases are washed with water and then with a NaHCO3 solution to neutrality. After drying over sodium sulphate, filtering and evaporating, 6.3 g of crude demethylation product are obtained. Flash chromatography on silica (elution: CH2Cl2/acetone 9/1) makes it possible to isolate 550 mg of 5-(4-hydroxy-3,5-dimethoxyphenyl)-9-hydroxy-5,8,8a,9-tetrahydro-5aH-furo[3′,4′:6,7]naphtho[2,3-d][1,3]dioxol-6-one, that is to say 4′-demethylepipodophyllotoxin of formula (Va). 1.10·g of 5-(3,4-dihydroxy-5-methoxyphenyl)-9-hydroxy-5,8,8a,9-tetrahydro-5aH-furo[3′,4′:6,7]naphtho[2,3-d][1,3]dioxol-6-one (Analysed: C20H18O8.0.15H2O; calculated: C %, 61.74; H %, 4.74. found: C %, 61.67; H %, 4.68), and then 1.9 g of 9-hydroxy-5-(3,4,5-trihydroxyphenyl)-5,8,8a,9-tetrahydro-5aH-furo[3′,4′:6,7]naphtho[2,3-d][1,3]dioxol-6-one are also isolated. The latter compound has a proton NMR spectrum with the following characteristics: 1H NMR (d6-DMSO) δ 8.65 (m, 2H), 7.95 (m, 1H), 6.71 (s, 1H, H5), 6.47 (s, 1H, H8), 5.98 (d, 2H, J=2 Hz, OCH2O), 5.93 (s, 2H, H2′, H6′), 4.68 (d, 1H, J=3.2 Hz, H4), 4.34 (t, 1H, J=8 Hz, H11a), 4.29 (d, 1H, J=5.2 Hz, H1), 4.16 (dd, 1H, J=8 Hz, J′=10 Hz, H11b), 3.17 (dd, 1H, J=5.2 Hz and J′=14 Hz, H2), 2.76 (m, 1H, H3).

来源