Catalytic Alkene Difunctionalization via Imidate Radicals

Abstract

The first catalytic strategy to harness imidate radicals has been developed. This approach enables alkene difunctionalization of allyl alcohols by photocatalytic reduction of their oxime imidates. The ensuing imidate radicals undergo consecutive intra- and intermolecular reactions to afford (i) hydroamination, (ii) aminoalkylation, or (iii) aminoarylation, via three distinct radical mechanisms. The broad scope and utility of this catalytic method for imidate radical reactivity is presented, along with comparisons to other N-centered radicals and complementary, closed-shell imidate pathways.

The Persistent Radical Effect in Organic Synthesis

“…Consequently, these methods are not ideal representatives of PRE‐steered processes, and the selectivity obtained for the radical–radical cross‐coupling step can be poor. Nevertheless, acceptable yields of the desired cross‐coupling product can be achieved if an excess of the precursor of the radical showing the longer‐lifetime—the cyanoarene (10 equiv and 5 equiv)—is used.…”

“…[96c] In addition to the many examples dealing with redoxneutral processes,t here are also procedures in which both radical species are generated by reduction using as toichiometric reducing reagent. [98] As radical generation is decoupled in such processes,t he two different radicals are not formed at equal rates.C onsequently,t hese methods are not ideal representatives of PRE-steered processes,a nd the selectivity obtained for the radical-radical cross-coupling step can be poor.N evertheless,a cceptable yields of the Figure 19. Radical-radical cross-couplingreaction with cyanoarenes 66 using photoredox catalysis.…”

Visible‐Light‐Induced Hydroxysulfurization and Alkoxysulfurization of Styrenes in the Absence of Photocatalyst: Synthesis of β‐Hydroxysulfides and β‐Alkoxysulfides

“…[7] Photoinitiated difunctionalizations of carbon-carbon multiple bonds have been used intensively to produce structurally diverse molecules. [8] Research on the direct conversion of different groups of combined alkenes cannot be accomplished without organic dyes or transition-metal complexes as photosensitizers. [9] To identify practical visible-lightpromoted difunctional transformations in the absence of photocatalyst presents a significant challenge.…”

Der “Persistent Radical Effect” in der organischen Chemie

“…Nichtdestotrotz konnten die gewünschten Kreuzkupplungsprodukte in akzeptablen Ausbeuten erhalten werden, wenn der Vorläufer für das Radikal mit der längeren Lebensdauer – das Cyanoaren – im Überschuss (10 Äquiv . und 5 Äquiv …”