2-Indanone → Indene

A 3-neck 500 mL round-bottomed flask fitted with a condenser and an addition funnel was charged with 2.62 g (0.11 mol) of Mg turnings and 20 mL of anhydrous Et2O. Slow addition of a solution of 25.10 g (0.09 mol) of 3,5-bis(trifluoromethyl) bromobenzene in Et2O (100 mL), followed by refluxing for 30 min, gave a brown-grey solution of the aryl Grignard reagent. The solution was cooled to room temperature, filtered over a plug of Celite and evacuated to yield a brown oil. Toluene (40 mL) was added and the suspension cooled to 0° C. whereupon a solution of 2-indanone (9.22 g, 0.07 mol) in toluene (60 mL) was added dropwise to give a tan-brown slurry. This mixture was warmed to room temperature and stirred for an additional 3 hours. After cooling to a 0° C. it was quenched with 150 mL of water. Hexane (200 mL) was added and the reaction mixture neutralized with 5M HCl. The organic layer was separated, and the aqueous layer was extracted with two 50-mL portions of hexane. The combined organic layers were washed with two 50-mL portions of brine and dried over anhydrous magnesium sulfate. After filtration over Celite, the solvent was removed under vacuo yielding 21.5 g (89% based on 2-indanone) of 2-(bis-3,5-(trifluoromethyl)phenyl)indanol as an off-white solid. 1H NMR (DCDl3, 23° C., 400 Mhz): d 8.05 (s, 2H), 7.80 (s, 1H), 7.5-7.0 (M, 4H), 3.41 (m, 4H), 2.21 (s, 1H, OH). Under argon, this alcohol (21.5 g, 0.06 mol) and p-toluene-sulfonic acid monohydrate (800 mg) were dissolved in toluene (250 mL) and the solution was heated to reflux for 6 hours to afford 14.4 g, (70%) of 2-(bis-3,5-(trifluoromethyl)-phenyl) indene upon recrystallization from diethyl ether/hexane at -18° C. 1H NMR (CDCl3, 23° C., 400 Mhz): d 8.01 (s, 2H), Arf), 7.75 (s, 1H, Arf), 7.52 (d, J=7 Hz, 1H), 7.47 (d, J=7 Hz, 1H), 7.43 (s, 1H), 7.33 (dd, 2J=7 Hz, 1H), 7.27 (dd, 2J- 7 Hz, 1H), 2.83 (s, 2H). 13C NMR (CDCl3, 23° C., 100 Mhz): d 144.3 (s), 143.1 (s), 138.0 (s), 132.1 (q 2JC-F =33 Hz), 130.1 (d, JC-H =167 Hz), 127.0 (dd), JC-H =160 Hz, 2JC-H =7 Hz), 126.0 (dd, JC-H =159 Hz, 2JC-H =7 Hz)m 125.2 (brd, JC-H =162 Hz), 123.9 (dd, JC-H =156 Hz, 2JC-H =9 Hz), 123.4 (q, JC-F =273 Hz, CF3), 121.8 (dd, JC-H =160 Hz, 2JC-H =8 Hz), 120.6 (brd, JC-H =167 Hz), 38.9 (td, JC-H =127 Hz, 2JC-H =7 Hz, CH2). C,H analysis: Anal. Found (Calcd): C, 62.45 (62.20); H 3.01 (3.07).

1. filtrationfiltered over a plug of Celite
2. customevacuated
3. customto yield a brown oil
4. additionwas added dropwise
5. customto give a tan-brown slurry
6. temperatureThis mixture was warmed to room temperature
7. temperatureAfter cooling to a 0° C. it
8. customwas quenched with 150 mL of water
9. additionHexane (200 mL) was added
10. customThe organic layer was separated
11. extractionthe aqueous layer was extracted with two 50-mL portions of hexane
12. washThe combined organic layers were washed with two 50-mL portions of brine
13. dry with materialdried over anhydrous magnesium sulfate
14. filtrationAfter filtration over Celite
15. customthe solvent was removed under vacuo
16. customyielding 21.5 g (89% based on 2-indanone) of 2-(bis-3,5-(trifluoromethyl)phenyl)indanol as an off-white solid
17. temperaturethe solution was heated
18. temperatureto reflux for 6 hours

ORD record

ord-afb0482d92e64e3389cb1fb1913d9c8e

Source dataset

uspto-grants-1999_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05969070