Reaktion #216364

Reaktionsgleichung

4-hydroxyacetophenone

3-chloro-3-methyl butyne

water

sodium hydroxide

→

compound

Ausbeute 34.3%

6-Acetyl-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran

Ausbeute 34.3%

Lösungsmittel

methylene chloride

methanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe organic layer was separated
2. 2
   EinengenThe combined extracts were concentrated in vacuo
3. 3
   Waschenwashed with 1N sodium hydroxide (3×250 ml), brine (200 ml)
4. 4
   Trocknendried over magnesium sulfate
5. 5
   SonstigeThe solvent was evaporated in vacuo
6. 6
   workup.DISSOLUTIONthe residue was dissolved in 1,2-dichlorobenzene (40 ml)
7. 7
   Temperaturheated
8. 8
   Temperaturat reflux temperature for four hours
9. 9
   SonstigeThe solvent was removed by distillation at atmospheric pressure
10. 10
    workup.DISTILLATIONthe residue was distilled under reduced pressure (b.p. 140°-150° C. at 2.0 mm)

Vorschrift

To a solution of 95% 4-hydroxyacetophenone (13.6 g, 100 mmol), 3-chloro-3-methyl butyne (17.4 g, 170 mmol) in methylene chloride (75 ml) was added water (75 ml), sodium hydroxide (6.4 g, 160 mmol), and Triton B (40% in methanol, 23.0 g, 52 mmol). The reaction mixture was stirred at room temperature for six days. The organic layer was separated, the aqueous phase was reextracted with methylene chloride (2×200 ml). The combined extracts were concentrated in vacuo, the residue was taken up in ethyl acetate (500 ml) washed with 1N sodium hydroxide (3×250 ml), brine (200 ml) and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was dissolved in 1,2-dichlorobenzene (40 ml) and heated at reflux temperature for four hours. The solvent was removed by distillation at atmospheric pressure using a vigreaux column and the residue was distilled under reduced pressure (b.p. 140°-150° C. at 2.0 mm) to provide the title A compound (7.0 g) as a light yellow solid. 1H NMR (CDCl3) δ7.75 (dd, J=2.3 & 8.8 Hz, 1H), 7.73 (d, J=2.4 Hz, 1H), 6.78 (d, J=8.8 Hz, 1H), 6.35 (d, J=10.0 Hz, 1H), 5.66 (d, J=9.9 Hz, 1H), 2.53 (s, 3H), 1.45 (s, 6H); 13C NMR (CDCl3) δ196.7, 157.4, 131.1, 130.2, 126.8, 121.6, 120.6, 116.0, 77.5, 28.3, 26.2.

Quelle