4-Toluenesulfonyl chloride → Tert-butoxycarbonyl-4-(4-toluenesulfonyloxyethyl)-2,2-dimethyloxazolidine

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Reaction Steps

Dry, freshly crystallised p-toluenesulphonyl chloride (1.86 g, 9.8 mmol) and 4-dimethylaminopyridine (10 mg, 0.082 mmol) were added to a solution of alcohol 5 (2.00 g, 8.15 mmol) and triethylamine (2.6 ml, 18.75 mmol) in dichloromethane (20 ml) at 5° C. with stirring. The resulting solution was protected from moisture and kept at 5° C. until all the starting material 5 had reacted (33 h, TLC). A colourless solid, presumably triethylamine hydrochloride, crystallised out of the reaction, and was filtered away. The filtrate was diluted with dichloromethane to a volume of 90 ml, and washed with water (2×20 ml), brine (20 ml), dried over Na2SO4, and concentrated to give the crude tosylate 7 as white solid. This material was purified by dissolving in ether (ca. 330 ml), filtering through celite 545 on a wad of cotton wool to give 2.95 g (90%) of 7. 1H NMR (200 MHz, CDCl3) 7.78 (m, 2H), 7.35 (d, 2H), 4.09 (m, 2H), 4.09 (m, 2H), 3.90 (m, 2H), 3.73 (m, 1H), 2.95 (m, 2H), 1.51 (s, 6H), 1.44 (s, 9H).

Provenance & Evidence