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-c94f4a570c62418a84c0053c8bfcab32

Source dataset

uspto-grants-2004_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06770672B1