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。
A Brønstedacid catalyzed redox arylation of ynamides that employs aryl sulfoxides as the arylating agents is reported. This metal‐free transformation proceeds at room temperature and efficiently affords α‐arylated oxazolidinones in a redox‐neutral, atom‐economic fashion.
4‐chirality transfer from sulfur to a carbon stereocenter through a sulfonium [3,3]‐sigmatropic rearrangement. This reaction delivers α‐arylated thioesters and amides under mild conditions in an atom‐economical manner. The products are formed in high yields with enantiomeric ratios up to 99.5:0.5. Quantum chemical calculations suggest a mechanism for the chirality transfer from sulfur to carbon and explain