反应详情

A solution of 13.0 g (45.6 mmol) of 44 in 150 ml of anhydrous THF was added dropwise with 100 ml of DIBAL-H (1 M/hexane, 100 mmol, 2.2 eq.) at −78° C. over a period of 30 min, and after completed addition the solution was stirred for two more hours. Thereafter, excess reagent was destroyed by adding 7 ml of isopropanol (evolution of hydrogen). This was added with 200 ml of K—Na tartrate solution (1.77 M), followed by slow thawing to RT overnight. The batch was subsequently transferred into a separating funnel and diluted with 300 ml of MTBE and 100 ml of water. After phase separation, the aqueous phase was extracted with 2×100 ml of MTBE, and the combined organic phases were subsequently dried over MgSO4. Following filtration over a short silica gel column, the solvent was removed under vacuum to obtain 12.2 g of α-hydroxycarbamate 207 (42.3 mmol, 93%) as a colorless oil that was reacted without further purification. An analytical sample was obtained by column chromatography over silica gel (EE/CH 1:2).

1. additionaddition the solution
2. customThereafter, excess reagent was destroyed
3. additionby adding 7 ml of isopropanol (evolution of hydrogen)
4. additionThis was added with 200 ml of K—Na tartrate solution (1.77 M)
5. customThe batch was subsequently transferred into a separating funnel
6. additiondiluted with 300 ml of MTBE and 100 ml of water
7. customAfter phase separation
8. extractionthe aqueous phase was extracted with 2×100 ml of MTBE
9. dry with materialthe combined organic phases were subsequently dried over MgSO4
10. filtrationfiltration over a short silica gel column
11. customthe solvent was removed under vacuum