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Reaction of B(4)‐acylmethyl o‐carborane with 2‐azido‐1,3‐dimethylimidazolinium hexafluorophosphate (ADMP) in the presence of 1,8‐diazabicyclo[5.4.0]‐undec‐7‐ene (DBU) in acetonitrile at 25 °C for 3 h produced a wide range of o‐carboranyl‐acyl‐substituted diazo compounds in high yields with good functional group tolerance. [ABSTRACT FROM AUTHOR]

An efficient synthetic method for structurally various isochromenoindolones has been demonstrated through Rh(III)‐catalyzed C−H activation followed by a cyclization reaction of N‐methoxyarylamides with 3‐diazooxindoles. The sequential reaction involves the streamlined formation of C−C and C−O bonds in one pot. The present method provides a broad range of isochromenoindolones as a new privileged scaffold in moderate to good yields with the release of methoxyamine and molecular nitrogen and has the benefits of a broad substrate scope and good functional group tolerance. [ABSTRACT FROM AUTHOR]

Palladium(II)‐catalyzed N‐acylation was demonstrated through the reaction of N−H sulfoximines with a variety of aryl, heteroaryl, and aryl halides using W(CO)6 as a source of carbon monoxide, affording N‐acylated sulfoximines in good to excellent yields. Moreover, alkenyl bromides underwent palladium(II)‐catalyzed N‐acylation reactions with N−H sulfoximines, leading to the formation of N‐cinnamoyl sulfoximines. This method has the advantages of a broad substrate scope, high functional group tolerance, simple operation, and chemoselectivity between chloride and bromide. [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed oxidative [4+2] cyclization reactions were developed from the C−H activation reaction of N‐methoxyazulene‐1‐ and 2‐carboxamides with symmetrical and unsymmetrical alkynes under a molecular oxygen atmosphere, producing azulenopyridinone derivatives with novel azulene skeletons in good to excellent yields with a wide substrate scope and excellent functional group tolerance. [ABSTRACT FROM AUTHOR]

An efficient rhodium(III)‐catalyzed N−H insertion reaction is developed from the reaction of phosphoryl amides with α‐aryl diazoesters under aerobic and mild conditions, which produce α‐phosphoryl amino esters in good to excellent yields with high selectivity, a broad substrate scope, and a good functional group tolerance. Also, Rh(III)‐catalyzed N−H insertion reaction of alkenyl phosphonic amides with α‐aryl diazoesters was successful. [ABSTRACT FROM AUTHOR]

Rh(III)-catalyzed B(4)-azo coupling reactions of o -carborane acids with aryl diazonium tetrafluoroborates have been developed, leading to the regioselective formation of B(4)-azo-coupled o -carboranes. Moreover, B(4)-azo-coupled o -carboranes can be further functionalized by introducing a second azo group, producing B(4)-C(1)-di(arylazo) o -carborane. The B(4)-azo group as an efficient directing group enables catalytic C-H amidation reactions, providing a new synthetic route for complex o -carborane derivatives.

Iridium(III)-catalyzed regioselective B(4)-H amination is developed from the reaction of o -carborane acids with sulfilimines without any oxidants under mild conditions, which leads to a wide range of B(4)-H aminated o -carboranes in good yields with a broad substrate scope. Moreover, the selective B(3,6)-diamination reaction of the o -carborane acid was achieved. The present reaction is attractive from a practical point of view because dibenzothiophene is quantitatively recovered and reused.

Regiodivergent transition metal-catalyzed B(4)- and C(1)-selenylation reactions of o -carboranes have been demonstrated. Namely, Ru(ii)-catalysis selectively generated B(4)-selenylated o -carboranes from the reaction of o -carborane acids with arylselenyl bromides with the release of carbon dioxide. In contrast, Pd(ii) catalysis provided exclusively C(1)-selenylated o -carboranes from the decarboxylative reaction of o -carborane acids with diaryl diselenides. In contrast to previous milestones in this area, these reactions demonstrate broad substrate scope with excellent yields. Combination of these methods leads to the formation of B(4)-C(1)-diselenylated o -carboranes. DFT studies revealed the mechanism of the Ru-process, with initial selenylation of the carborane cluster discovered to be essential for an energetically reasonable decarboxylation. This results in selenylation on the B(4) position prior to the decarboxylation event at C(1). This contrasted with the Pd-process in which the ready decarboxylation at C(1) leads to selenylation at C(1)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A direct B(4)-H monoacyloxylation via a Pd-catalyzed regioselective B(4)-H activation of o -carborane acids with phenyliodonium dicarboxylates was developed, and a series of B(4)-H monoacyloxylated o -carboranes decorated with active groups were synthesized with moderate to good yields as well as excellent selectivity. In addition, a direct B(4,5)-H diacetoxylation from o -carborane acids with phenyliodonium diacetate was demonstrated.

Rhodium-catalyzed oxidative [4 + 2] cyclization reactions through the C-H activation of azulene carboxylic acids as nonbenzenoid aromatic compounds with symmetrical and unsymmetrical alkynes were developed under aerobic conditions, which produced azulenolactone derivatives with a wide substrate scope and excellent functional group tolerance. Interestingly, azulenic acids in reaction with alkynes underwent iridium-catalyzed [2 + 2 + 2] cyclization accompanied by decarboxylation to afford tetra(aryl)-substituted benzoazulene derivatives. The reactivity order for C-H activation reaction is greater toward azulene-6-carboxylic acid, azulene-1-carboxylic acid, and azulene-2-carboxylic acid. For the first time, the expansion of azulenes having directing group as nonbenzenoid aromatic compounds for C-H activation was successful, indicating that nonbenzenoid aromatic compounds can be used as good substrates for the C-H activation reaction. Therefore, the research area of C-H activation will certainly expand to nonbenzenoid aromatic compounds in future.