Electrochemical Cage Activation of Carboranes

Abstract

Carboranes are boron-carbon molecular clusters that possess unique properties, such as their icosahedron geometry, high boron content, and delocalized three-dimensional aromaticity. These features render carboranes valuable building blocks for applications in supramolecular design, nanomaterials, optoelectronics, organometallic coordination chemistry, and as boron neutron capture therapy (BNCT) agents. Despite tremendous progress in this field, stoichiometric chemical redox reagents are largely required for the oxidative activation of carborane cages. In this context, electrosyntheses represent an alternative strategy for more sustainable molecular syntheses. It is only in recent few years that considerable progress has been made in electrochemical cage functionalization of carboranes, which are summarized in this Minireview. We anticipate that electrocatalysis will serve as an increasingly powerful stimulus within the current renaissance of carborane electrochemistry.

Asymmetric synthesis of metallacarboranes using a traceless chiral auxiliary

“…Carboranes are a class of boron-rich cage-like molecular clusters possessing three-dimensional aromaticity. Due to their unique properties in chemical bonding, electronic regulation, thermal stability, shape, lipophilicity etc., 1 in the past decades, great efforts have been made to functionalize [2][3][4] and employ carboranes as the key structural units in polymers, 5,6 optoelectronic materials, [7][8][9] pharmaceuticals, [10][11][12] coordination chemistry 13 and catalysis. 14 Among the known carboranes, o-carborane (o-C 2 B 10 H 12 ), has been the most easily accessible and most studied precursor.…”

Pd-Catalyzed Oxidative Dehydrogenative Cross Coupling of Cage B–H/B–H Bonds at Room Temperature: Synthesis of Bis(o-carborane)s

“…In the last decade, catalyzed dehydrogenative cross coupling of cage B–H bonds has received much attention. Considerable progress has recently been made in the catalytic functionalization of cage B–H bonds at specific position(s) of carboranes . For example, dehydrogenative coupling of carboranes has become a useful method for the formation of cage B–C and B–heteroatom bonds .…”

Fragile intermediate identification and reactivity elucidation in electrochemical oxidative α-C(sp3)–H functionalization of tertiary amines

“…1B ). Electrosynthesis has emerged as a broadly applicable redox tool, 7 offering a mild way to drive chemical reactions without the requirement of stoichiometric oxidants. In this case, tertiary amines can be oxidized to nitrogen radical cations via a single electron transfer (SET) process, followed by deprotonation, yielding α-amino C(sp 3 ) radicals ( Fig.…”