A transition metal-free, regioselective, and stereoselective diboration of alkynamides is presented which employs the differentially protected diboron reagent, pinBBdan. The reaction occurs through diboron activation <i>via </i>the deprotonated amide followed by C-B bond formation through two successive five-membered transition states. The resulting diboration products have an uncommon <i>(E) </i>stereoconfiguration and bear the Bdan and Bpin moieties solely at the α and β positions, respectively. Due to the significant different in Lewis acidity between diaminonapthalene- and pinacol-ligated boron, the products of this reaction show exclusive chemoselectivity in downstream cross-coupling reactions; this allows for construction of tetrasubstituted alkenes with a set geometry. Moderate to good yields are reported for a variety of substrates, which include electron rich and deficient arylpropiolamides, N-substituted phenylpropiolamides, and alkynamides bearing a heterocycle or straight-chain alkyl group off the triple bond.

Substrate-assisted, transition metal-free diboration of alkynamides with an unsymmetrical diboron reagent

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.