Enantioselective radical cascade cyclization via Ti-catalyzed redox relay

05 May 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Radical cascade cyclization reactions provide an efficient method for the construction of polycyclic architectures with multiple stereogenic centers. However, achieving enantioselectivity control of this type of reaction is a challenging task. Here, we report an enantioselective cyclization of polyfunctional substrates containing cyclopropyl ketone and alkyne units, wherein the stereochemical outcome is directed by a chiral Ti(salen) catalyst. This transformation was proposed to proceed via a radical cascade process involving the reductive ring-opening of the cyclopropyl ketone followed by two annulation events entailing cyclization of the ensuing alkyl radical onto the alkyne and subsequent addition of the incipient vinyl radical to the Ti(IV)-enolate.

Keywords

Radical cascade cyclization
asymmetric catalysis
titanium catalysis
salen ligands
polycyclic molecules

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