Tetrahydrofuran → 2-(3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-ol

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).

1. temperatureThe reaction mixture was heated
2. temperatureto reflux for 8 h
3. customThe reaction was quenched with water (1.5 mL)
4. additiontreated with NaBO3.4H2O
5. extractionDiethyl ether (4 mL) and the reaction mixture were extracted with CH2Cl2 (2×20 mL)
6. concentrationThe organic layers were concentrated to a clear oil that
7. customwas purified by silica gel chromatography
8. washeluting with ethyl acetate (50%, v/v) in hexane

ORD record

ord-89b5775f5aeb4e3a9d75230e3cb48871

Source dataset

uspto-grants-2004_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06703384B2