反应详情

温度

0 °C

A solution of 19 g (0.063 mol) of the hydroxydione XIIIa in 200 ml dry ether was cooled to 0° C. To this was added 10 ml triethylamine followed by a solution of 14 g (0.063 mol) of 2-mesitylenesulfonyl chloride in 50 ml of ether. After stirring 30 minutes at 0° C the solution was allowed to warm to room temperature. It was then washed with cold H2O, 1N HCl, brine, then dried over anhydrous CaCl2 and concentrated at 32° C under reduced pressure. The light colored oily residue of the enol sulfonate XIVa (Ar = 2,4,6-C6H2 -) was not purified but was used directly in the next step. It was taken up in 300 ml absolute ethanol and cooled to 0° C. 2.4 g (0.063 mol) of sodium borohydride was added and the reaction stirred overnight. The reaction was then quenched with 1 molar oxalic acid, the solution concentrated to a third of its volume, and the residue partitioned between ether and H2O. The ether phase was separated, dried over anhydrous MgSO4, and evaporated under reduced pressure to give a brown residue. This was taken up in 100 ml dry THF and stirred with 5.7 g (0.063 mol) of oxalic acid and 8.5 g (0.063 mol) of sodium oxalate for 16 hours. Filtration and evaporation gave a residue that was twice chromatographed; first on silicic acid and second on silica gel, both times eluting with 9:1 v:v benzene:ethyl acetate. This gave 5 g of the hydroxy ketone XVa as a pale yellow oil; nD19 = 1.5499.

1. temperatureto warm to room temperature
2. washIt was then washed with cold H2O, 1N HCl, brine
3. dry with materialdried over anhydrous CaCl2
4. concentrationconcentrated at 32° C under reduced pressure
5. customThe light colored oily residue of the enol sulfonate XIVa (Ar = 2,4,6-C6H2 -) was not purified
6. temperaturecooled to 0° C
7. stirringthe reaction stirred overnight
8. customThe reaction was then quenched with 1 molar oxalic acid
9. concentrationthe solution concentrated to a third of its volume
10. customthe residue partitioned between ether and H2O
11. customThe ether phase was separated
12. dry with materialdried over anhydrous MgSO4
13. customevaporated under reduced pressure
14. customto give a brown residue
15. filtrationFiltration and evaporation
16. customgave a residue that
17. customwas twice chromatographed
18. washfirst on silicic acid and second on silica gel, both times eluting with 9:1 v