Réaction #2634

Équation de réaction

4-hydroxy-2-cyclopentenone

triethylamine

tert-butyldimethylsilyl chloride

→

title compound

Rendement 83.2%

4-tert-butyldimethylsiloxy-2-cyclopentenone

Rendement 83.2%

Solvants

HCl

tetrahydrofuran

tetrahydrofuran

Conditions de réaction

Traitement

1. 1
   Températuremaintaining the temperature at or below 10° C
2. 2
   AutreThe phases are separated
3. 3
   Extractionthe aqueous phase is extracted with heptane (2×1L)
4. 4
   Lavagewashed with aqueous HCl (0.5N, 2×500 mL)
5. 5
   Séchage5% sodium bicarbonate (500 mL), then brine (500 mL), dried over anhydrous magnesium sulfate
6. 6
   Filtrationfiltered
7. 7
   Concentrationconcentrated under vacuum (40° C., 20 mmHg)

Mode opératoire

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 (1L) 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, 1L). The phases are separated and the aqueous phase is extracted with heptane (2×1L). 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) δ7.48 (dd, J=5.7, 2.4 Hz, 1H), 6.20 (d, J=5.7 Hz, 1H), 4.95-4.99 (m, 1H), 2.72 (dd, J=18.2, 6.0 Hz, 1H), 2.25 (dd, J=18.2, 2.3 Hz, 1H), 0.88 (s, 9H), 0.11 (s, 6H); 13C 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).

Source