Metal-catalyzed B-H acylmethylation of pyridylcarboranes: access to carborane-fused indoliziniums and quinoliziniums

Metal-catalyzed mono-acylmethylation of pyridylcarboranes has been realized using alpha-carbonyl sulfoxonium ylides as a coupling partner. The reaction features high efficiency, excellent site-selectivity and good functional group tolerance. In the presence of pyridyl and enolizable acylmethyl groups, a post-coordination mode has been proposed and validated by in situ high resolution mass spectroscopy (HRMS) to rationalize the unique mono-substitution. Post-functionalization at the newly incorporated alkyl site provides additional utility of this method, including the construction of carborane-fused indoliziniums and quinoliziniums. We believe that these mono-alkylated carboranes, together with their post-functionalized derivatives, may find applications in luminescent materials and drug discovery in the near future.

Automated summary

Metal-catalyzed mono-acylmethylation of pyridylcarboranes has been achieved using alpha-carbonyl sulfoxonium ylides, showing high efficiency, excellent site-selectivity, and good functional group tolerance. A post-coordination mode has been proposed to rationalize the unique mono-substitution, validated by in situ high resolution mass spectroscopy. The method also allows for post-functionalization at the newly incorporated alkyl site, expanding the utility of this reaction for the construction of carborane-fused indoliziniums and quinoliziniums with potential applications in luminescent materials and drug discovery.