A Versatile Route to Acyl (MIDA)Boronates

A modular approach to highly functional acyl (MIDA)boronates is described. It involves the generation of the hitherto unknown radical derived from acetyl (MIDA)boronate and its capture by various alkenes, including electronically unbiased, unactivated alkenes. In contrast to the anion of acetyl (MIDA)boronate, which has not so far been employed in synthesis, the corresponding radical is well behaved and readily produced from the novel & alpha;-xanthyl acetyl (MIDA)boronate. This shelf-stable, easily prepared solid is a convenient acyl (MIDA)boronate transfer agent that provides a direct entry to numerous otherwise inaccessible structures, including latent 1,4-dicarbonyl derivatives that can be transformed into B(MIDA) substituted pyrroles and furans. A competition experiment indicated the acyl (MIDA)boronate substituted radical to be more stable than the all-carbon acetonyl radical but somewhat less reactive in additions to alkenes. Exploiting the reactivity of the novel acetyl (MiDA)boronate radical allows access to a broad range of acyl (MIDA)boronates, which in suitable cases can be converted into B(MIDA) substituted furans and pyrroles.image

Automated summary

This study presents a modular approach to highly functional acyl (MIDA)boronates. The radical derived from acetyl (MIDA)boronate is generated and captured by various alkenes, providing access to numerous otherwise inaccessible structures. The reactivity of the acetyl (MIDA)boronate radical allows the synthesis of a wide range of acyl (MIDA)boronates, which can be further transformed into B(MIDA) substituted furans and pyrroles.