Functionalized Organocuprates:
Structures of Lithium and Magnesium Grignard 2-Methoxyphenylcuprates
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Abstract
Lithium and magnesium Grignard diorganocuprates incorporating
the functionalized aryl group 2-methoxyphenyl have been prepared and
structurally characterized in the solid state. [Cu<sub>4</sub>Li<sub>2</sub>(C<sub>6</sub>H<sub>4</sub>OMe-2)<sub>6</sub>(THF)<sub>2</sub>] (<b>2</b>) and [Cu(C<sub>6</sub>H<sub>4</sub>OCH<sub>3</sub>-2)<sub>2</sub>Mg(THF)<sub>2</sub>X] (<b>3-X</b>; X = Cl, Br)
all exhibit coordination of the s-block metal center by the methoxy
oxygen, resulting in the formation of novel aggregates and favoring
contact ion pair structures. In contrast, separate ion pair structures
had previously been observed under similar conditions for nonfunctionalized
arylcuprates. The magnesium organocuprates <b>3-Cl</b> and <b>3-Br</b> are of particular interest, being rare examples of structurally
characterized Grignard-derived organocuprates and the first examples
of functionalized Grignard organocuprates. All reported organocuprates
undergo oxidative aryl coupling in the presence of O<sub>2</sub> or
PhNO<sub>2</sub> to give 2,2′-dimethoxybiphenyl
