Carbon Dioxide → Bicyclo(2.2.1)heptane-7-carboxylic acid

To a solution of 4-4′-di-t-butylbiphenyl (8.25 g, 31 mmol) in anhydrous tetrahydrofuran (70 mL) under a nitrogen atmosphere was added freshly cleaned lithium wire (0.21 g, 30 mmol). The resulting mixture was stirred at room temperature for 15 minutes to initiate reaction, then cooled in an ice bath and stirred for an additional 4 hours. The resulting blue solution was cooled with a dry ice/acetone bath and a solution of 7-bromo-bicyclo[2.2.1]heptane (2.0 g, 11.4 mmol) in anhydrous tetrahydrofuran (5 mL) was added in one portion. The reaction mixture was stirred for 20 minutes, during which time the blue color changed to orange. Solid dry ice was then added to the reaction, which became colorless. The dry ice bath/acetone bath was removed and the reaction was stirred for 2 hours, during which time it came up to room temperature. 2.5 N aqueous sodium hydroxide (200 mL) was added and the mixture was stirred for 5 minutes. The layers were separated and the aqueous layer was extracted twice with diethyl ether (50 mL). The aqueous layer was then made acidic by addition of concentrated HCl and extracted with three portions of diethyl ether (75 mL). The combined organic layers were dried over anhydrous magnesium sulfate and concentrated to yield the desired compound of formula (VIII) as a white solid (1.54 g, 96%), mp=74–75 ° C. (lit. mp=77.5–785° C., J. Am. Chem. Soc. 1954, 76, 4072).