Abstract

In the lecture, it will be shown, that readily generated vinyl boron ate complexes, generally used as substrates in the Suzuki-Miyaura coupling, are efficient radical acceptors to conduct electron-catalyzed modular synthesis comprising a radical polar cross over step. Along these lines, dienyl boron ate complexes react with high efficiency with various C-radicals at the d-position, and the polar cross over rearrangement process delivers valuable allyl boronic esters as products. This conceptual approach has recently been successfully also applied to the development of a novel method for the preparation of highly enantioenriched -chiral ketones. Hydrogen atom transfer induced boron retaining coupling of organoboronic esters and organolithium reagents is discussed as a straightforward method for the -C-H functionalization of alkyl boronic esters.

In addition, it will be shown that bis(catecholato)diboron (Cat₂B₂) is a highly efficient C-radical trapping reagent. For example, this reactivity was applied to establish a transition-metal-free radical alkene 1,2-carboboration reaction. It is further shown that alkyl and aryl iodides react with Cat₂B₂ upon simple irradiation to the corresponding alkyl and aryl boronic esters. Alcohols, if appropriately activated, can also be transformed to boronic esters via radical pathways. Finally, migration of boron groups and of aryl moieties from boron in B-ate complexes to C-radicals will be addressed.