Palladium-Catalyzed Direct B—H Oxygenation: Facile Synthesis of o-Carboranofuranones
Chenyang Guo , Zaozao Qiu , Zuowei Xie
Chinese Journal of Chemistry ›› 2024, Vol. 42 ›› Issue (23) : 3083 -3087.
Palladium-Catalyzed Direct B—H Oxygenation: Facile Synthesis of o-Carboranofuranones
Recent advances in transition metal-catalyzed o-carborane B—H activation have led to the rapid development of various methodologies for cage boron functionalization. For catalytic cage B—H acyloxylation, intermolecular oxygenation gave products with different regioselectivities (B(3)-, B(4)-, and B(8, 9)-selectivities). Herein, an efficient palladium-catalyzed direct cage B(4)–H oxygenation of o-carboranylacetic acids has been achieved, where the carboxylic group serves as not only a directing group, but also a coupling partner. A wide range of substituted o-carboranylacetic acids have been cyclized via the formation of B(4)-O bond to give the corresponding γ-lactones in modest to excellent yields. A Pd(IV) intermediate is proposed to be involved in the catalytic cycle. This work offers valuable references for the BH/OH dehydrocoupling reactions under mild conditions to produce carborane-featuring functional molecules.
Carborane / B—H activation / Oxygenation / Catalysis / Transition metal / Palladium / Cross-coupling / Regioselectivity
2024 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
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