Oxidation of carboranes by thallium(III) in the presence of palladium(II) as a new route to biscarboranes

Advances in the Synthesis of Biscarboranes

“…However, the resulted 9,9'-bis(1,2-Me 2 -ocarborane) was only identified by mass spectrometry and has not been obtained in pure form, and the relative yield of 35 % was calculated based on GLC analysis. [18] Though these problems have not been addressed, this is the first example for synthesis of BBC from o-carborane directly (Scheme 7).…”

“…Based on the electrophilic characteristic of B(9)−H bond of o ‐carborane, by employing Tl(OCOCF 3 ) 3 as electrophilic reagent to form the B(9)‐Tl complex, the 9,9′‐bis(1,2‐Me 2 ‐ o ‐carborane) has been synthesized in the presence of catalytic amount of Pd(OAc) 2 in CF 3 COOH. However, the resulted 9,9′‐bis(1,2‐Me 2 ‐ o ‐carborane) was only identified by mass spectrometry and has not been obtained in pure form, and the relative yield of 35 % was calculated based on GLC analysis [18] . Though these problems have not been addressed, this is the first example for synthesis of BBC from o ‐carborane directly (Scheme 7).…”

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

“…However, there are only four reports on the synthesis of biscarboranes linked by a B–B bond. In 1983, Usyatinskii and co-workers disclosed the first example of Pd-catalyzed B–H/B–H homocoupling of 1,2-Me 2 - o -carborane using stoichiometric Tl­(OCOCF 3 ) 2 . The method for preparing 9,9′-bis­( m -carborane) was reported using 9,9′-bis­( m -carboranyl)­mercury .…”

Catalytic Oxidative Dehydrogenative Coupling of Cage B–H/B–H Bonds for Synthesis of Bis(o-carborane)s

“…C,11 B{H}, and11 B NMR spectra (PDF)Accession Codes CCDC 1904327 and 1904329 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.NotesThe authors declare no competing financial interest.■ ACKNOWLEDGMENTSThis work was supported by the National Natural Science Foundation of China (Grant 21602182), the Longshan academic talent research supporting program of SWUST…”

“…For biscarborane connected by a B–B bond, there were some controversies on the reproducibility in its early stage . Until 1983, the 9,9′-bis­(1,2-Me 2 - o -carborane) was precisely synthesized in the presence of a catalytic amount of Pd­(OAc) 2 and stoichiometric Tl­(OCOCF 3 ) 2 by Usyatinskii and coworkers (Scheme b). Then, the 9,9′-bis­( m -carborane) was further synthesized from 9,9′-bis­( m -carboranyl) mercury (Scheme c).…”