Reacción #76472

Ecuación de reacción

6-vinylchroman

THF

9-BBN

→

6-(2-hydroxyethyl)chroman

Rendimiento 24.0%

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe reaction mixture was heated
2. 2
   Temperaturato reflux for 8 h
3. 3
   OtroThe reaction was quenched with water (1.5 mL)
4. 4
   workup.ADDITIONtreated with NaBO3.4H2O
5. 5
   ExtracciónDiethyl ether (4 mL) and the reaction mixture were extracted with CH2Cl2 (2×20 mL)
6. 6
   ConcentraciónThe organic layers were concentrated to a clear oil that
7. 7
   Otrowas purified by silica gel chromatography
8. 8
   Lavadoeluting with ethyl acetate (50%, v/v) in hexane

Procedimiento

A solution of the 6-vinylchroman intermediate (0.12 g, 0.27 mmol) in anhydrous THF (1 mL) was cooled to 0° C. and treated with 9-BBN (0.60 mL, 0.5 M in THF, 0.3 mmol). The reaction mixture was heated to reflux for 8 h. The reaction was quenched with water (1.5 mL) and treated with NaBO3.4H2O and the resulting slurry was stirred overnight. Diethyl ether (4 mL) and the reaction mixture were extracted with CH2Cl2 (2×20 mL). The organic layers were concentrated to a clear oil that was purified by silica gel chromatography eluting with ethyl acetate (50%, v/v) in hexane. This yielded the desired 6-(2-hydroxyethyl)chroman intermediate as a colorless oil (30 mg, 24%). 1H-NMR (CDCl3/TMS, ppm): 0.87 (m, 12H, 4a′-, 8a′-, 12a′-, 13′-CH3), 1.0-1.6 (m, 24H, 4′-, 8′-, 12′-CH, 1′-, 2′-, 3′-, 5′-, 6′-, 7′-, 9′-, 10′-, 11′-CH2, 2a-CH3), 1.81 (m, 2H, 3-CH2), 2.17, 2.24, 2.28 (3×s, 9H, 5a-, 7a-, 8a-CH3), 2.68 (t, J=6.8 Hz, 2H, 4-CH2), 3.01 (t, J=7.5 Hz, 2H, Ar—CH2), 3.74 (t, J=7.5 Hz, 2H, OCH2); 13C-NMR (CDCl3, ppm): 12.0, 15.1, 16.0 (5a-, 7a-, 8a-CH3), 19.6, 19.7 (CH3), 20.6, 21.0 (CH2), 22.6, 22.7 (CH3), 23.8 (2a-CH3), 24.4, 24.8 (CH2), 28.0 (CH), 31.2 (3-CH2), 32.7, 32.8 (CH), 37.3, 37.4, 37.5, 39.4, 40.0 (CH2), 62.2 (OCH2), 72.6 (2-C), 116.8, 122.3, 124.9, 132.4, 133.9 (aryl C), 150.1 (aryl C—O); HRMS (CI, m/z): 458.412154 (M+H+, Calc. for C31H54O2 458.412384).

Fuente