An air stable, highly efficient Dtbpf palladium carbonate precatalyst was developed to catalyze borylation of arybromides with HBpin. Comparing with palladium chloride precatalyst, the new system is more active at the catalyst induction period which represents a completely different catalyst activation mechanism. Arylbromides with electron-withdrawing functional group were considered challenge substrates due to undesired dehalogenation side reaction, however with the current catalyst and additives, several electron-deficient arybromides can be borylated in good to excellent yield. The catalyst also shows a general substrate scope with a variety of electronic and steric substitutes and more than 20 aryl and hetero-arylbromides are tested and gave synthetic useful yields of arylborates. Several biaryl-compound were also prepared in one-pot borylation/Suzuki sequential reactions using arylchlorides and arylbromides as coupling partners. Furthermore, with the aid of Xray and NMR experimental studies, for the first time a cationic metathesis pathway was uncovered that could pave the way for better understanding and designing more efficient catalyst.

Air-stable palladium precatalyst for forylation of arylhalides with HBpin and experimental evidences on cationic metathesis mechanism

249th National Meeting (2015)

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