反应详情

1.4 g sodium nitrite in 5 ml H2O are added dropwise within 10 minutes under ice-cooling and stirring to 6.8 g of the product of step (b) in 200 ml 0.2N HCl. The reaction mixture is stirred under ice-cooling for 15 minutes and added dropwise unter nitrogen to 100 ml refluxing 0.4N HCl within 15 minutes. Stirring is continued for 10 minutes. The mixture is then cooled, rendered alkaline with saturated K2CO3 solution and extracted about 7 times with 9:1 CH2Cl2 /l CH3OH, whereby the black residue remains in the aqueous phase. The organic phase is dried (Na2SO4), evaporated, the resulting foam is chromatographed on silica gel using 80:20:0.7 CH2Cl2 /CH3OH/NH3 to afford the heading compound as a brown resin (pure 8α-compound by NMR).

1. temperaturecooling
2. temperaturecooling for 15 minutes
3. additionadded dropwise unter nitrogen to 100 ml
4. stirringStirring
5. temperatureThe mixture is then cooled
6. extractionextracted about 7 times with 9:1 CH2Cl2 /l CH3OH, whereby the black residue
7. dry with materialThe organic phase is dried (Na2SO4)
8. customevaporated
9. customthe resulting foam is chromatographed on silica gel using 80:20:0.7 CH2Cl2 /CH3OH/NH3
10. customto afford the heading compound as a brown resin (pure 8α-compound by NMR)