反应详情

0.8489 g (6.15 mmol) of the compound of part (a) was suspended in POCl3 (5 ml) and heated under reflux under a Drierite guard tube. Complete dissolution did not occur after 11/2 hours and so Et2NPh (0.5 ml) was added and the reflux was continued for an additional 11/2 hours. Complete solution had occurred to give a wine colored solution. This was concentrated in vacuo to ~2 ml and then added dropwise to ice-H2O (50 ml). The pH of the mixture was adjusted to 3-4 (pH paper) with NH4OH and the solution was extracted with CH2Cl2 (2×50 ml). The pooled organic phases were dried (MgSO4), filtered, and evaporated to an off-white residue. This solid was dissolved in CH2Cl2 -MeOH and adsorbed onto a little silica gel by evaporation. The solid was placed atop a dry-packed silica gel 60 column (2.5×33.0 cms) and development was initiated with EtOAc:hexanes 1:3 (500 ml). Then, EtOAc:hexanes 1:1 was utilized; fractions containing the required product, were pooled and evaporated to dryness in vacuo to give the title compound as crystalline plates. NMR (CDCl3, δ from TMS): 2.23 (S, 5-CH3), 2.50 (S, 4.6-CH3 'S).

1. temperatureheated
2. temperatureunder reflux under a Drierite guard tube
3. dissolutionComplete dissolution
4. additionwas added
5. custom2 hours
6. customto give a wine colored solution
7. concentrationThis was concentrated in vacuo to ~2 ml
8. additionadded dropwise to ice-H2O (50 ml)
9. extractionthe solution was extracted with CH2Cl2 (2×50 ml)
10. dry with materialThe pooled organic phases were dried (MgSO4)
11. filtrationfiltered
12. customevaporated to an off-white residue
13. dissolutionThis solid was dissolved in CH2Cl2 -MeOH
14. customadsorbed onto a little silica gel by evaporation
15. additionfractions containing the required product
16. customevaporated to dryness in vacuo