Hydrochloric Acid → 4-((tert-Butyl(dimethyl)silyl)oxy)cyclopent-2-en-1-one

Participants

Reaction Conditions

Reaction Steps

A solution of 4-hydroxy-2-cyclopentenone (191 g, 1.95 mol, prepared in example 1) and triethylamine (430 mL, 3.09 mol) in anhydrous tetrahydrofuran (1 L) is treated with 4-dimethylaminopyridine (4.90 g, 40.0 mmol). The solution is cooled to 0° C. and treated portionwise, over 10 minutes, with tert-butyldimethylsilyl chloride (278 g, 1.84 mol) maintaining the temperature at or below 10° C. The reaction is then allowed to stir overnight at room temperature. It is then poured into aqueous HCl (0.5N, 1 L). The phases are separated and the aqueous phase is extracted with heptane (2×1 L). The organic phase and organic extracts are combined, washed with aqueous HCl (0.5N, 2×500 mL), then 5% sodium bicarbonate (500 mL), then brine (500 mL), dried over anhydrous magnesium sulfate, filtered and concentrated under vacuum (40° C., 20 mmHg) to provide the title compound (325 g). This is purified by Kugelrohr distillation (70°-80° C., 1 mmHg) to provide the title compound (282 g, 72% yield) as a light yellow oil, Rf =0.55, 20% ethyl acetate/hexane, GC retention time is 14.97 minutes; 1H NMR (CDCl3) δ 7.48 (dd, J=5.7, 2.4 Hz, 1 H), 6.20 (d, J=5.7 Hz, 1 H), 4.95-4.99 (m, 1 H), 2.72 (dd, J=18.2, 6.0 Hz, 1 H), 2.25 (dd, J=18.2, 2.3 Hz, 1 H), 0.88 (s, 9 H), 0.11 (s, 6 H); 13 C NMR (CDCl3) δ 206.4, 163.8, 134.4, 70.8, 44.9, 25.7, 25.6, 18.0; IR (neat) νmax 2957, 2931, 2887, 2858, 1725 cm-1 ; MS (EI) m/e (% relative intensity) 212 (M+, 5), 155 (M+ -57, 100).

Provenance & Evidence