Alder Addition of Perchlorobenzyne Benzobarrelene

Submitted by Neil J Hales, Harry Heaney, John H Hollinshead, and Pritpal Singh  

A Telrachlorobenzobarrelene. A carefully dried, 5-1., three-necked, round-bottomed flask is equipped with a large magnetic 

B Benzobarrelene. A dry 1-1, three-necked, round-bottomed flask IS equipped with a magnetic stirring bar, a combined gas-inlet tube and rubber septum, a 500-ml. pressure-equalizing dropping funnel, and a reflux condenser connected to a Nujol bubbler The flask is charged with 500 ml of dry tetrahydrofuran (Note 14) and 17 g. (0.74 mole) of sodium wire with a diameter of ca 0.5 mm The mixture is stirred and heated at reflux under an atmosphere of argon or nitrogen, and 50 ml of freshly distilled tert-butyl alcohol IS added. Immediately afterward a solution of 15 g (0 051 mole) of 

1 The dropping funnel must be arranged so that the drops fall directly into the solution and not onto the side of the flask The checkers used a 4-1., tour-necked flask equipped with a mechanical stirrer and a ground-glass stirring assembly and carried out the reaction on four-fifth s scale. 

Dry ethyl ether and dry, thiophene-free benzene were prepared by the submitters according to procedures presented in ref. 2. 

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