Electrooxidative B−H Functionalization of nido‐Carboranes

Abstract

An atom-economical method for the direct B À H functionalization of nido-carboranes (7,8-nido-C 2 B 9 H 12 À)h as been developed under electrochemical reaction conditions.I n this reaction system, anodic oxidation serves as ag reen alternative for traditional chemical oxidants in the oxidation of nido-carboranes.N ot ransition-metal catalyst is required and different heteroatoms bearing al one pair are reactive in this transformation. Coupling nido-carboranes with thioethers, selenides,t ellurides,N-heterocycles,p hosphates,p hosphines, arsenides and antimonides demonstrates high site-selectivity and efficiency.I mportantly,n ido-carboranes can be easily incorporated into drug motifs through this reaction protocol.

Palladium‐Catalyzed Cascade Deboronation/Regioselective B−P Coupling of closo‐Carboranes

“…[7] However, these reactions largely require stoichiometric amounts of oxidants, which can undergo either formation of stable metallacarboranes [2] or oxidative cage decomposition. [8] In addition, the undesired formation of inseparable mixture of B( 9)/B (10) or B(9)/B(11)-isomers frequently limits the application of this approach. Recently, Ackermann [9] and Yan [10] disclosed the direct BÀ H functionaliza-tion of nido-carboranes by the electrooxidative reaction, respectively, albeit largely limited to symmetric 7,8-disubstituted nido-carborane substrates.…”

“…[8] In addition, the undesired formation of inseparable mixture of B( 9)/B (10) or B(9)/B(11)-isomers frequently limits the application of this approach. Recently, Ackermann [9] and Yan [10] disclosed the direct BÀ H functionaliza-tion of nido-carboranes by the electrooxidative reaction, respectively, albeit largely limited to symmetric 7,8-disubstituted nido-carborane substrates. However, the nido-carborane substrates in these reactions need to be pre-prepared from closo-carborane precursors.…”

Elektrochemische Carborankäfig‐Aktivierung

“…Anders als in der elektrokatalysierten Nitrogenierung von nido-Carboranen berichtete Yan kürzlich über eine ähnliche elektrooxidative BÀ H-Funktionalisierung von nido-Carboranen mit unterschiedlichen Heteroatomen, welche ein freies Elektronenpaar besitzen (Schema 6). [29] Diese elektrochemische Oxidationsmethode ermöglicht die selektive BÀ S-, BÀ Se-, BÀ Te-, BÀ N-, BÀ P-, BÀ As-und BÀ Sb-Kupplung mit einer großen Anzahl von Anwendungen und einer hohen Toleranz gegenüber funktionellen Gruppen in einem benutzerfreundlichen, ungeteilten Zellaufbau (7 a-Schema 12. Diversifizierung im späten Synthesestadium und Kontrollexperimente der cupra-elektrokatalysierten CÀ H-Chalkogenierung.…”

Synthesis and Reactivity of Cyclic Oxonium Derivatives of nido-Carborane: A Review

“…This approach is widely used for the synthesis of C-substituted derivatives of nido-carborane, as well as derivatives containing substituents at the lower belt of the nido-carborane cage [40]. There are several general methods for the synthesis of B-substituted derivatives with substituents in the upper belt of the nido-carborane cage; however, most of them are used to obtain asymmetrically substituted derivatives [9-X-7,8-C 2 B 9 H 11 ] − [41][42][43][44][45][46][47][48][49].…”