Tetra diboron metal activation

It seems that all the efforts to activate tetra(alkoxy)diboron compounds are justified since the model CI2B—BCI2 reagent, which develops borylation without metal activation, is too difficult to handle. However, the progress in this field has opened a new window toward the activation of tetra(alkoxy) diboron compounds in a metal-free context by the formation of Lewis add—base adducts and their addition to unsaturated substrates can be performed with total chemo-, regjo-, and stereoselectivity. 

Therefore, this historical prospection toward the activation of diboron has moved from direct reaction of CI2B—BCI2 with alkenes to the current methodology that circumvent the activation of tetra(alkoxy)diboron reagents with simple LBs. But metal activation has been and still is a... 

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