Metal-catalyzed cross-coupling reactions have become ubiquitous in organic chemistry for the efficient formation of C–C bonds. A major component for the success of reactions such as the Suzuki-Miyaura cross-coupling is the broad availability of the necessary starting aryl halides and aryl boronic acid reagents. In particular, aryl boron reagents are very attractive due to their mild nucleophilicity, low toxicity, and long-term stability. Traditional methods to synthesize aryl boron reagents make use of highly reactive Grignard reagents or perform lithium-halogen exchange procedures using strong bases such as <i>n-</i>BuLi. While metal-catalyzed methodologies have been developed over the last decade, many of those transformations require the use of harsh reaction conditions, which limit their functional group compatibility and scope. We surmised that using palladium/copper dual-catalysis would help overcome current reaction limitations. The cooperative aspect of the two catalysts enables facile transformation of aryl halides at room temperature and under mild reaction conditions. Interestingly, early mechanistic work indicates that the catalytic cycle for aryl iodides and aryl bromides differs and possess different hurdles to overcome for efficient generation of the desired products. We will present the substrate scope, functional group compatibility, current limitations, and mechanistic work for this transformation.

Palladium/copper cooperative-catalysis for the synthesis of aryl boronic esters

2019 Spring National Meeting

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