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

Abstract

Nucleophilic ring-opening reactions of cyclic oxonium derivatives of anionic boron hydrides are a convenient method of their modification which opens practically unlimited prospects for their incorporation into various macro- and biomolecules. This contribution provides an overview of the synthesis and reactivity of cyclic oxonium derivatives of nido-carborane as well as half-sandwich complexes based on it.

Charge-compensated nido-carborane derivatives in the synthesis of iron(ii) bis(dicarbollide) complexes

“…The next challenge was the synthesis of 8,8′-substituted oxonium derivatives of iron bis(dicarbollide). It is known that cyclic oxonium derivatives of nido -carborane open easily under the action of various nucleophiles, 42 while acyclic dialkyloxonium derivatives easily lose one alkyl group. 43 Despite this, we found that under mild conditions, the reactions of both cyclic and acyclic oxonium derivatives of nido -carborane with FeCl 2 lead to the corresponding 8,8′-bis(dialkyloxonium) derivatives of iron( ii ) bis(dicarbollide) [8,8′-(RRO) 2 -3,3′-Fe(1,2-C 2 B 9 H 10 ) 2 ] (RR = (CH 2 ) 4 ( 17 ), (CH 2 ) 2 O(CH 2 ) 2 ( 18 ), (CH 2 ) 5 ( 19 ); R = Et ( 20 )) in good (60–71%) yields (Scheme 3).…”

New Azido Coumarins as Potential Agents for Fluorescent Labeling and Their “Click” Chemistry Reactions for the Conjugation with closo-Dodecaborate Anion

“…An effective approach to the functionalization of the closo -dodecaborate anion is the opening of its cyclic oxonium derivatives by nucleophiles [ 76 ]. This approach is widely used for the synthesis of its various functional derivatives and attachment to biomolecules [ 64 , 77 , 78 ], and has also been used to modify other polyhedral boron hydrides such as the closo -decaborate anion [ 64 ], nido -carborane [ 79 ], and cobalt and iron bis(dicarbollides) [ 80 ]. In particular, the synthesis of the earlier described coumarin derivatives of the closo -dodecaborate anion is based on the opening of oxonium rings with hydroxy groups at various positions of the coumarin heterocycle [ 72 , 73 , 74 ].…”

The Rise of Boron-Containing Compounds: Advancements in Synthesis, Medicinal Chemistry, and Emerging Pharmacology

“…Whereas there are abundant comprehensive monographs describing systematic ways of generating C–C or C–X cross couplings, monographs for their boron cluster counterparts, for B–C and B–X couplings, are rare. To the best of our knowledge, only a review dealing with the different cross coupling methodologies used so far to produce B–C, B–P, B–N, and B–S bonds in the most popular boron cluster (dianionic [B 12 H 12 ] 2– , monoanionic [Co­(C 2 B 9 H 11 ) 2 ] − , and neutral, o -C 2 B 10 H 12 ) has been available since 2013, but recently, other reviews dealing with halogenated icosahedral boranes, carboranes and metallabis­(dicarbollides), carboranylphosphine ligands, the synthesis and reactivity of oxonium derivatives of nido -carboranes, functionalization of o -carboranes via carboryne intermediates, as well as on metallabis­(dicarbollides) have appeared.…”

“…Over the past 30 years, new protocols for C−C cross coupling are mostly based on metal-catalyzed reactions. 773−776 777 but recently, other reviews dealing with halogenated icosahedral boranes, carboranes and metallabis-(dicarbollides), 778 carboranylphosphine ligands, 779 the synthesis and reactivity of oxonium derivatives of nidocarboranes, 780 functionalization of o-carboranes via carboryne intermediates, 780 as well as on metallabis(dicarbollides) 780 have appeared. 9.2.2.…”