, purified by silica gel column chromatography (eluent: DCM/MeOH, 98/2, v/v). The amine-borane complex 21-BH3 (209 mg; 0.816 mmol) was obtained as beige crystals. Yield 70%; mp 99-100 °C

, H NMR (200 MHz, CDCl3), vol.1, 1027.

, Wiley-Interscience Series in Mass Spectrometry, Proteomic Biology Using LC-MS, pp.255-255

+. , Cristallographic data are available in supporting information

, 1044, 981; 1 H NMR (500 MHz, CD3OD) ? 5.11 (dd, 1H, 2 JH-H = 13.5 Hz, 3 JH-P = 7.7 Hz, OCH'), 5.08 (dd, 1H, 2 JH-H = 13.5 Hz, 3 JH-P = 7

N. Hz,

. Mhz,

, Conversion table for cholesterol concentration (mg/100 ml ? mmol/l), The Biology of Cholesterol and Related Steroids, vol.3229, p.xiv, 1981.

, CH2CH2Cl)2), 3.17 (s, 9H, CH2N + (CH3)3); 13 C NMR (126 MHz, CD3OD) ? 147.18 (CArNO2), 136.36 (CArCH=CH), 133.17 (d, 3 JC-P = 6.5 Hz, CArCH2O), vol.132

+. ,

, N-dimethylpropan-1-amine borane complex (24a-BH3) was prepared from alcohol 21-BH3 (133 mg, 0.519 mmol) as described for the preparation of 14a-BH3. The crude product was purified by silica gel chromatography (eluent: DCM/EtOH, 96/4, v/v) to yield compound 24a-BH3 (150 mg, 0.629 mmol) as an oil. Yield 63%

, IR (ATR) ? cm -1 3231, 0980.

H. Nmr, 500 MHz, CDCl3) ? 5.14 (dd, 1H, 2 JH-H = 13.4 Hz, 3 JH-P = 7

. H-=-13, 4 Hz, 3 JH-P = 6.4 Hz

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