Homocoupling transition-metal-free

A transition metal-free homocoupling of monomagnesium or diorganomagnesium compounds complexed with LiCi are oxidatively dimerized using the readily available oxidation agent 3,3 ,5,5 -tetra-ter/-butyldiphenoquinone (118 Scheme 2-44). The resulting biphenyldiolate 119 can be easily reoxidized to 118 by air. The method allows the synthesis of various biaryls, diynes, and dienes with retention of the double-bond configuration. 

Scheme 2-44. Transition metal-free homocoupling using the diphenoquinone 118.

Transition metal-free homocoupling of ethyl 4-iodobenzoate... 

---