The synthesis of pyridines through direct intermolecular cycloaddition of alkynes and nitriles is a contemporary challenge in organic synthesis. A Brønsted acid mediated formal [2+2+2] cycloaddition of heteroalkynes and nitriles was developed that proceeds under mild conditions. This constitutes a modular approach to highly substituted pyridine cores.
Ynamide Preactivation Allows a Regio- and Stereoselective Synthesis of α,β-Disubstituted Enamides
作者:Lucas L. Baldassari、Aurélien de la Torre、Jing Li、Diogo S. Lüdtke、Nuno Maulide
DOI:10.1002/anie.201709128
日期:2017.12.4
Activate first, attack later: Thanks to an ynamide preactivation strategy, otherwise incompatible reagents can be used to prepare α,β-disubstituted enamides with high regio- and stereoselectivity. Mechanistic analysis reveals the intermediacy of a triflate-bound species as a solution-stable, effective keteniminium reservoir, which is amenable to the subsequent addition of organometallic reagents.
Palladium‐Catalyzed Silylcyanation of Ynamides: Regio‐ and Stereoselective Access to Tetrasubstituted 3‐Silyl‐2‐Aminoacrylonitriles
作者:Pierre Hansjacob、Frédéric R. Leroux、Vincent Gandon、Morgan Donnard
DOI:10.1002/anie.202200204
日期:2022.3.28
Tetrasubstituted 2-aminoacrylonitriles (α-enaminonitriles) are underinvestigated building blocks due to the lack of methodologies to synthesize them in a controlled manner. A general access to these valuable scaffolds accompanied by mechanistic investigations and DFT calculations is described. This highly regio- and stereoselective strategy relies on the use of the first intermolecular silylcyanation
Hydrative Aminoxylation of Ynamides: One Reaction, Two Mechanisms
作者:Alexandre Pinto、Daniel Kaiser、Boris Maryasin、Giovanni Di Mauro、Leticia González、Nuno Maulide
DOI:10.1002/chem.201706063
日期:2018.2.16
Organic synthesis boasts a wide array of reactions involving either radical species or ionic intermediates. The combination of radical and polar species, however, has not been explored to a comparable extent. Herein we present the hydrative aminoxylation of ynamides, a reaction which can proceed by either a polar-radical crossover mechanism or through a rare cationic activation. Common to both processes
有机合成拥有涉及自由基物质或离子中间体的广泛反应。然而,自由基和极性物种的结合尚未得到相当程度的探索。在这里,我们提出了 ynamides 的水合氨氧基化反应,该反应可以通过极性-自由基交叉机制或通过罕见的阳离子活化进行。这两个过程的共同点是持久自由基 TEMPO 及其氧化的氧代铵衍生物TEMPO+ 的多功能性。通过实验和深入的 DFT 计算阐明了这些过程的独特机制。
Harnessing ynamide activation to access deuterated carbonyls
A simple and convenientsynthesis of α-bisdeuterated imides is reported, hinging on the transient formation of keteniminium ions by treatment of ynamides with TfOD, followed by trapping with D2O. The products are obtained in good yields and with a high degree of deuterium incorporation. Gram-scale reaction and further derivatization without deuterium erosion highlight the synthetic utility of this