Vinylboronic acid derivatives play a pivotal role as key build-ing blocks in the construction of polysubstituted alkenes, which are important structural motifs present in medicines, natural products, and materials science. Control of the stereo- and regio-chemistry in these products is typically mediated by cross-coupling reactions such as the Suzuki-Miyaura reaction. As such, vinylboronic acid derivatives bearing multiple boron moieties with chemoselective reactivity are highly desirable. Diboration of alkynes with bis(pinacolato)diboron (B2pin2) has been intensely investigated using transition metal complexes and provides access to 1,2-cis-vinyldiboronates. In this presentation, we report a substrate-assisted diboration of propargyl amides using an unsymmetrical pinacolato-1,8-diaminonaphthalenato diboron (pinBBdan). The developed reaction is transition metal-free and proceeds in a regio- and stereoselective fashion to exclusively afford trans vinyldiboronates in good to excellent yields. Bdan and Bpin are installed on the α and β carbons, respectively, using a wide variety of substrates. Mechanistic and theoretical studies will be discussed.

Transition metal-free activation and intramolecular trans diboration of propargylamides using unsymmetrical diboron

253rd National Meeting (2017)

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