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, 2′-, 3′-, 5′-, 6′-, 7′-, 9′-, 10′-, 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-058c8ae357854be08d6f650b9aae281f

Source dataset

uspto-grants-2014_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08664264B2