Quinone → 3-Acetyl-3a,7a-dihydro-7a-(phenylethynyl)benzofuran-2,5(3H,4H)-dione

Temperatur

-78 °C

Phenylacetylene (1 mL, 9.3 mmole) was placed in dry THF (10 mL) in a dry, 50 mL, 3-necked, round bottomed flask fitted with a mechanical stirrer, thermometer and argon inlet. The solution was cooled to -78° C. and treated with 1.6M n-butyllithium (5.8 mL, 9.3 mmole) in hexane. The reaction was stirred at -78° C. for 30 min, warmed to 0° C., then recooled to -78° C. Benzoquinone (1 g, 9.3 mmole) and dry THF (10 mL) were added, under argon, to a separate 100 mL, 3-necked, round bottomed flask. The mixture was cooled to -78° C. and treated with the lithium phenylacetylide solution prepared above. The flask which contained the lithium phenyacetylide solution was washed with dry THF (10 mL) and the solvent was added to the larger flask. Upon addition of the lithium phenylacetylide, the reaction mixture turned dark blue. The reaction was stirred for 20 min at -78° C. then dry DMPU (18 mL, 0.15 mole) was added. The reaction was stirred for five min before diketene (0.8 mL, 10.2 mmole) in THF (10 mL) was added. The reaction was stirred for 1 hr at -78° C., then allowed to warm to room temperature, stirred overnight and concentrated in vacuo. The residue was treated with water (50 mL) and saturated ammonium chloride (50 mL), acidified with 3N hydrochloric acid, and extracted with CH2Cl2 (4×75 mL). The combined CH2Cl2 extracts were washed with water (50 mL) and brine (2×50 mL), dried over anhydrous sodium sulfate, filtered and concentrated. The residue was dissolved in Et2O (150 mL), and the solution was washed with water (3×50 mL and 1×75 mL) and brine (75 mL), dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The residue was purified by flash column chromatography (silica gal; eluting with hexane: EtOAc (4:1) to yield 2.4 g (88%) of the title compound. Crystallization from acetone/ethyl acetate gave a white solid, m.p. 168°-171° C. (dec).

1. custom3-necked, round bottomed flask fitted with a mechanical stirrer
2. temperaturewarmed to 0° C.
3. customrecooled to -78° C
4. temperatureThe mixture was cooled to -78° C.
5. customprepared above
6. washwas washed with dry THF (10 mL)
7. additionthe solvent was added to the larger flask
8. additionUpon addition of the lithium phenylacetylide
9. stirringThe reaction was stirred for 20 min at -78° C.
10. additionwas added
11. stirringThe reaction was stirred for 1 hr at -78° C.
12. temperatureto warm to room temperature
13. stirringstirred overnight
14. concentrationconcentrated in vacuo
15. additionThe residue was treated with water (50 mL) and saturated ammonium chloride (50 mL)
16. extractionextracted with CH2Cl2 (4×75 mL)
17. washThe combined CH2Cl2 extracts were washed with water (50 mL) and brine (2×50 mL)
18. dry with materialdried over anhydrous sodium sulfate
19. filtrationfiltered
20. concentrationconcentrated
21. dissolutionThe residue was dissolved in Et2O (150 mL)
22. washthe solution was washed with water (3×50 mL and 1×75 mL) and brine (75 mL)
23. dry with materialdried over anhydrous sodium sulfate
24. filtrationfiltered
25. concentrationconcentrated in vacuo
26. customThe residue was purified by flash column chromatography (silica gal
27. washeluting with hexane: EtOAc (4:1)

ORD-Eintrag

ord-5f86705192bd4fe288f61e2b1fd6ae40

Quelldatensatz

uspto-grants-1989_01

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US04798893