Asymmetric synthesis of multiple quaternary stereocentre-containing cyclopentyls by oxazolidinone-promoted Nazarov cyclizationsElectronic supplementary information (ESI) available: Experimental details and NMR spectra of all newly synthesized compounds. X-ray crystal data for (3S)-23 and E-24. Details and further discussion of computational studies. CCDC 1814626 and 1814627. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8sc00031j

• Main Authors: Volpe, Rohan, Lepage, Romain J, White, Jonathan M, Krenske, Elizabeth H, Flynn, Bernard L
• Format: Journal Article
• Language: English
• Published: 23-05-2018
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c8sc00031j

Carbometalation of oxazolidinone (
Ox
)-substituted ynamides is used to generate highly substituted
Ox
-divinyl (and aryl vinyl) ketones for use in Nazarov cyclizations. The
Ox
-group serves as a remarkably effective chiral activating group, enabling the torquoselective Nazarov cyclization of these sterically congested substrates to be performed under mild conditions. It also serves as a charge-stabilizing group in the intermediate oxyallyl cation, suppressing undesired [1,2]-sigmatropic shifts of neighboring substituents and facilitating the regio- and stereoselective incorporation of nucleophiles to yield cyclopentanoids containing up to three contiguous all-carbon quaternary (4°) stereocentres.
Ox
-activated divinyl ketones undergo torquoselective Nazarov cyclization to give cyclopentanoids containing up to three new contiguous quaternary (4°) stereocentres.