反应详情

A mixture of R-[N,N′-bis(monoisopinocampheylborane)-N,N,N′,N′-tetramethylethylenediamine] (1.25 g, 3.0 mmol) in THF (5 mL) was treated with boron trifluoride etherate, stirred at room temperature for 1.5 hours, and filtered. The filter cake was washed with THF (2.5 mL). Half of the solution containing the free isopinocamphenylborane (1.5 mmol) was cooled to −25° C., treated with a solution of Example 275D (500 mg, 1.25 mmol) in THF (3 mL), stirred at −20° C. for 48 hours, warmed to 0° C., and quenched with methanol (0.5 mL). The solution was treated with 3M NaOH (1.1 mL), followed by 30% H2O2 (0.9 mL) dropwise, stirred for 1 hour at 50° C., cooled to room temperature, extracted with diethyl ether, dried (Na2SO4), filtered, and concentrated. The concentrate was purified by flash column chromatography on silica gel with 30% acetone/hexanes to give 300 mg (57% yield). MS (ESI) m/e 412 (M−H)−; 1H NMR (300 MHz, DMSO-d6) δ 10.02 (s, 1H), 7.69 (m, 1H), 7.63 (dt, 1H), 7.42 (m, 1H), 7.30 (dt, 1H), 7.0 (d, 1H), 6.92 (d, 1H), 4.73 (d, 1H), 3.85 (m, 1H), 2.95 (m, 1H), 2.82 (m, 1H), 2.6 (m, 1H), 1.81 (m, 1H), 1.69 (m, 1H), 0.98 (d, 3H).

1. filtrationfiltered
2. washThe filter cake was washed with THF (2.5 mL)
3. additionHalf of the solution containing the free isopinocamphenylborane (1.5 mmol)
4. temperaturewas cooled to −25° C.
5. stirringstirred at −20° C. for 48 hours
6. temperaturewarmed to 0° C.
7. customquenched with methanol (0.5 mL)
8. additionThe solution was treated with 3M NaOH (1.1 mL)
9. stirringstirred for 1 hour at 50° C.
10. temperaturecooled to room temperature
11. extractionextracted with diethyl ether
12. dry with materialdried (Na2SO4)
13. filtrationfiltered
14. concentrationconcentrated
15. customThe concentrate was purified by flash column chromatography on silica gel with 30% acetone/hexanes
16. customto give 300 mg (57% yield)