反应详情

1 g of podophyllotoxin I is dissolved in a mixture of 15 ml of CH2Cl2 and 5 ml of ethyl ether. A slight stream of gaseous hydrochloric acid is introduced into the solution for 15 min at -10° C. and then stirring is maintained at this temperature for 1 h. After evaporating the reaction mixture without heating, 0.54 g of D,L-methionine and then 5 ml of methanesulfonic acid are added. After dissolving and stirring for 1 h with return to ordinary temperature, the reaction mixture is plunged into a water-acetone mixture and then BaCO3 is added to neutrality. After extracting with ethyl acetate, separating by settling, drying over Na2SO4, filtering and evaporating under reduced pressure, a residue is obtained which is crystallized from ethyl ether to provide 0.5 g (Yd 52%) of white crystals of 4'-demethylepipodophyllotoxin exhibiting a homogeneous spot by TLC.

1. temperatureis maintained at this temperature for 1 h
2. customAfter evaporating the reaction mixture
3. temperaturewithout heating
4. addition0.54 g of D,L-methionine and then 5 ml of methanesulfonic acid are added
5. dissolutionAfter dissolving
6. stirringstirring for 1 h with return to ordinary temperature
7. additionBaCO3 is added to neutrality
8. extractionAfter extracting with ethyl acetate
9. customseparating
10. dry with materialdrying over Na2SO4
11. filtrationfiltering
12. customevaporating under reduced pressure
13. customa residue is obtained which
14. customis crystallized from ethyl ether