Oxaazabicyclooctene Oxides, Another Type of Bridgehead Nitrones: Diastereoselective Assembly from Acetylene Gas, Ketones, and Hydroxyl Amine

Elena Yu Schmidt; Inna V Tatarinova; Igor' A Ushakov; Alexander V Vashchenko; Boris A Trofimov

doi:10.1021/acs.joc.0c00742

Oxaazabicyclooctene Oxides, Another Type of Bridgehead Nitrones: Diastereoselective Assembly from Acetylene Gas, Ketones, and Hydroxyl Amine

J Org Chem. 2020 May 15;85(10):6732-6740. doi: 10.1021/acs.joc.0c00742. Epub 2020 May 7.

Authors

Elena Yu Schmidt¹, Inna V Tatarinova¹, Igor' A Ushakov¹, Alexander V Vashchenko¹, Boris A Trofimov¹

Affiliation

¹ A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Street, 664033 Irkutsk, Russia.

PMID: 32347720
DOI: 10.1021/acs.joc.0c00742

Abstract

Unique bridgehead nitrones, 8-oxa-6-azabicyclo[3.2.1]oct-6-ene 6-oxides, have been assembled diastereoselectively via acetyldihydropyrans, products of one-pot self-organization of two molecules of ketones and two molecules of acetylene, which after oximation undergo acid-catalyzed ring closure. The proposed mechanism includes the enol double-bond protonation, followed by intramolecular cyclization involving the interaction of the carbocation formed with a nitrogen atom. A broad range of substrates tolerate this facile transformation, in which the bridgehead nitrones were isolated in high yields.