Synthesis of oxaboranes via nickel-catalyzed dearylative cyclocondensation

We report Ni-catalyzed dearylative cyclocondensation of aldehydes, alkynes, and triphenylborane. The reaction is initiated by oxidative cyclization of the aldehyde and alkyne coupling partners to generate an oxanickelacyclopentene which reacts with triphenylborane to form oxaboranes. This formal dearylative cyclocondensation reaction generates oxaboranes in moderate-to-high yields (47-99%) with high regioselectivities under mild reaction conditions. This approach represents a direct and modular synthesis of oxaboranes which are difficult to access using current methods. These oxaboranes are readily transformed into valuable building blocks for organic synthesis and an additional class of boron heterocycles. Selective homocoupling forms oxaboroles, oxidation generates aldol products, and reduction and arylation form substituted allylic alcohols.

Automated summary

This study reports a nickel-catalyzed dearylative cyclocondensation reaction of aldehydes, alkynes, and triphenylborane. The reaction proceeds under mild conditions, generating oxaboranes with high regioselectivity and moderate-to-high yields. This approach provides a direct and modular synthesis of oxaboranes, which are difficult to access using current methods, and has important implications in the synthesis of valuable building blocks for organic synthesis.