Chloride → Bis(1,2-dimethylpropyl)borane

Temperature

0 °C

A solution of disiamylborane was prepared by mixing 35 mL of BH3THF (1 M in THF) and 35 mL of 2-methyl-2-butene (2 M in THF) at 0° C. followed by stirring at 0° C. for 75 minutes. To this solution was introduced 2R-carboethoxy-5-oxotetrahydrofuran dissolved in THF (6 mL). The resultant mixture was allowed to warm slowly to room temperature over a period of 2.5 hours and then was stirred for another 15 hours. Saturatedammonium chloride solution was added, followed by dilution with EtOAc. The above mixture was stirred for 10 minutes and then was transferred to a separatory funnel. The organic phase was washed successively with saturated NH4Cl, brine, and then was dried (Na2SO4). The solvent was removed on a rotary evaporator and the crude product obtained was purified by column chromatography (40% EtOAc-Hexanes). The desired products were isolated in 70% yield (2.05 g) as a 2:3 mixture of isomer epimeric at C5. Trace amount of the open form isomer was also detected (1H NMR). The title compounds displayed the following spectral characteristics: 1H NMR (CDCl3): δ 1.28 (t, 2H, J=7.1 Hz), 1.30 (t, 1H, J=7.1Hz), 1.85-2.70 (m, 4H), 2.59 (d, 0.33H, J=5.5Hz), 2.88 (d, 0.67H, J=3.1Hz), 4.15-4.65 (m, 2H), 4.57 (d of d, 0.33H, J=6.4, 8.3Hz), 4.70 (d of d, 0.67H, J=4.1, 8.7Hz), 5.59 (m, 0.33H), 5.74 (m, 0.67H).

1. temperatureto warm slowly to room temperature over a period of 2.5 hours
2. stirringwas stirred for another 15 hours
3. stirringThe above mixture was stirred for 10 minutes
4. customwas transferred to a separatory funnel
5. washThe organic phase was washed successively with saturated NH4Cl, brine
6. dry with materialwas dried (Na2SO4)
7. customThe solvent was removed on a rotary evaporator
8. customthe crude product obtained

ORD record

ord-42e704a059a3403281aa2f01497ba3a6

Source dataset

uspto-grants-1998_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05744596