反応 #5655

反応方程式

diborane

2-valeryl furan

[1,3,2] oxazaborole

HCl

→

product

収率 70.0%

(S)-1-(2-Furyl)-1-pentanol

収率 70.0%

溶媒

methanol

THF

ether

反応条件

後処理

1. 1
   workup.STIRRINGStirred for 0.5 h
2. 2
   その他white solid was precipitated out
3. 3
   workup.ADDITIONThe cloudy mixture was poured into 100 mL ether and 100 mL water
4. 4
   その他The organic layer was separated
5. 5
   洗浄washed with saturated sodium bicarbonate, water, brine
6. 6
   その他dried
7. 7
   ろ過filtered
8. 8
   その他The filtrate was evaporated to an yellowish oil which
9. 9
   その他was chromatographed
10. 10
    洗浄eluting with 10 % ethyl acetate in hexane

実験手順

10.4 mmol (10.4 mL) of diborane (1 M solution in THF) was added dropwise in a period of 10 m at room temperature to a solution of 2-valeryl furan (2.62 g, 17.2 mmol) and 1.68 mmol (4.2 mL) of (3aR)-1,3,3-triphenyl pyrrolidino [1,2-c] [1,3,2] oxazaborole (see E. J. Corey et al. J. Am. Chem. Soc. 1987, 109, 7925-26, 0.4M solution in THF) in 25 mL THF. The reaction mixture was stirred for 20 m and was cooled to 10° C. 6 mL methanol was cautiously added and followed by adding 62 mg HCl (by weight) in ether. Stirred for 0.5 h, white solid was precipitated out. The cloudy mixture was poured into 100 mL ether and 100 mL water. The organic layer was separated, washed with saturated sodium bicarbonate, water, brine, dried and filtered. The filtrate was evaporated to an yellowish oil which was chromatographed eluting with 10 % ethyl acetate in hexane to obtain 70% of the product. [α]25D =-13°, 60% ee by Mosher' ester analysis.

出典