Ynamides in Free Radical Reactions

Abstract

In this review we present the transformations that have been developed with ynamides and free radicals. These reactions involve carbon-, heteroatom-or even metalloid-centered radicals and include inter-and intra-molecular reactions. The scope and mechanism of these transformations are discussed in details, including the most recent examples relying on photoredox catalysis. 2.3. Initiation Through the Addition of an External Radical Species 3. Intermolecular Addition of Radicals on the Alkyne Moiety 3.1. Addition of Thiyl Radicals 3.2. Addition of Silyl and Germyl Radicals 3.3. Addition of Carbon Centered Radicals 3.4. Photocatalyzed Generation of Radicals 4. Conclusion

A general synthesis of azetidines by copper-catalysed photoinduced anti-Baldwin radical cyclization of ynamides

“…Based on the peculiar reactivity of ynamides 20 , 21 and their ability to participate in radical processes 22 , 23 , we hypothesized that these nitrogen-substituted alkynes might provide an excellent opportunity for the development of such a process. The presence of the nitrogen atom in between the radical centre and the triple bond could facilitate the 4-exo-dig cyclization by bringing the reacting centres in proximity, polarizing the triple bond and stabilizing the resulting vinyl radical (Fig.…”

Base‐Mediated Generation of Ketenimines from Ynamides: [3+2] Annulation with Azaallyl Anions

“…This reaction, named the Staudinger synthesis, set the template for accessing this particular heterocycle and inspired a myriad of synthetic variations [2] . Our group developed an imino‐variant of this transformation by using an ynamide [3–10] ( 1 a ) to generate in situ [11,12] a highly reactive ketenimine ( 2 a ) [13–15] which can engage in a [2+2] cycloaddition with a diaryl imine ( 3 a ) to give an azetidinimine (Scheme 1a) [16,17] . Exploring this transformation further, we found that when the same reaction conditions were applied to the homologous benzylimine 3 b , the formation of the expected azetidinimine was not observed.…”

Recent Progress in Enolonium Chemistry under Metal‐Free Conditions

“…[57] The radical mechanism provided by these conditions may display unconventional selectivity different from the closed-shell reactions. [58] In this account, recent developments in the reactions of αcarbonyl radicals will be summarized.…”