Homocoupling reactions natural product synthesis

In analogy to the reaction described in the previous section, iron-catalyzed homocoupling of aryl Grignard reagents can be achieved (Scheme 4-253). Two variations of this transformation have been described both using iron(III) chloride as catalyst. In the first procedure, the reaction is performed in tetrahydrofuran at low temperatures between -40 °C and 0 °C employing 1,2-diiodoethane as an oxidant in stoichiometric amounts. This method tolerates nitrile, ester, and nitro groups. An intramolecular version has been employed for the total synthesis of the natural product N-... 

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