Pyridine → 5,5,8,8-Tetramethyl-5,6,7,8-tetrahydro-1H-cyclopenta[b]naphthalene

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Reaction Steps

A 1 L round bottom flask fit with a magnetic stirrer, condenser, thermometer, and nitrogen inlet was charged with anhydrous toluene (7 mL, Aldrich), the crude 5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indan-2-ol (31.0 g, 0145 mol), pyridine (31.6 mL, 0.39 mol, Aldrich), and p-toluenesulfonyl chloride (30.4 g, 0.16 mol, Aldrich). The mixture was heated to reflux and cooled for GC analysis periodically for a total reflux time of 2 hours. The reaction was then quenched in 5% HCl (250 mL) and extracted into diethyl ether (200 mL). The ether extract was washed with 5% HCl (200 mL), 5% aqueous sodium bicarbonate (until neutral to pH paper), Water (2×200 mL), and dried over anhydrous magnesium chloride. Removal of solvents by rotary evaporation gave 23.0 g of crude product which was purified by chromatography on silica gel (60 g silica gel/hexane eluent) to give 5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indene (17.5 g, 92-99+% pure by GC). 1HNMR (CDCl3, 500 MHz) δ7.44 (s, 1H); 7.36 (s, 1H); 6.82 (br d, J=5.5 Hz, 1H); 6.47 (br d, J=5.5 Hz, 1H); 3.51 (s, 2H); 1.70 (s, 4H); 1.32 (s, 12H).

Provenance & Evidence