Synthetic study on indolic enamides

We report a facile method for preparing enamides, based on the Curtius rearrangement and acylation of alkenylcarbamate. Using this approach, total syntheses of coscinamides, chondriamides, and igzamide were achieved.     

Synthesis of enamides from aldehydes and amides

A range of double unsaturated amides (15, 19, and 21), obtained by cross-coupling reactions was reacted with aldehydes to hemiaminals. Heating the hemiaminals in the presence of Ac₂O and pyridine affected clean conversion to the corresponding enamides, such as 42, 45, and 47. Alternatively, N,S-acetals were prepared which were oxidized to the sulfones. Treatment with base also gave the enamides, favoring the cis-isomer. However, this method is less general. Application of these methods led to the natural products lansiumamide-A (30_cis), lansiumamide-I (31) and lansiumamide-B (32).     

Visible-light-promoted and photocatalyst-free trifluoromethylation of enamides

An efficient and practical method is developed for the trifluoromethylation of enamides using Umemoto’s reagent as the trifluoromethylating reagent. These reactions proceeded under visible light irradiation without any photocatalyst at room temperature in good chemical yields.     

Aqueous metal-free hydrothiolation of enamides and enecarbamates

An efficient and metal-free, anti-Markovnikov selective, hydrothioaltion reaction of enamides and enecarbamates in an aqueous medium is presented. This protocol is operationally simple, mild, and atom-economical. This process provides access to thioethers from available thiols and a variety of enamides and enecarbamates.     

Organocatalytic chemoselective asymmetric N-allylic alkylation of enamides

The first Lewis base-catalysed chemoselective asymmetric N-allylic alkylation of enamides with Morita-Baylis-Hillman carbonates has been developed, which affords multifunctional products in moderate to high enantioselectivity (up to 92% ee).     

An efficient synthesis of enamides from ketones

A new synthesis of enamides from ketones is disclosed that involves a phosphine-mediated reductive acylation of oximes. The resulting enamides are isolated in good yields (up to 89%) and excellent purity, permitting a subsequent hydrogenation to access enantiopure acetamides at catalyst loadings practical for large-scale applications.     

Interconversion and preparative separation of enantiomeric enamides

Barriers to rotation about the CN single bond of enamides (Table 1) are rationalised. The barriers of $\text{7}$ and $\text{8}$ allow separations of the enantiomers.     

FeCl3-promoted alkylation of indoles by enamides

An efficient iron-promoted alkylation of indoles with enamides has been accomplished under mild reaction conditions. The reaction proceeded with remarkable regioselectivity leading exclusively to substitution by indoles at α-position of enamides.     

Highly regioselective intermolecular hydroacylations of enamides with salicylaldehydes

Highly regioselective intermolecular hydroacylations of enamides under rhodium catalysis with monodentate phosphane ligands are reported for the first time. The presence of MeCN facilitates this novel C-C bond formation, and the electron-deficient phosphine P(p-F-Ph)(3) has proven most effective for the direct hydroacylation of 1-vinyl-2-pyrrolidinone. Accordingly, an atom-economic synthetic route to α-amido ketones from readily available substrates has been developed.     

Highly regioselective hydroformylation of enamides with phosphite ligands

The regioselective hydroformylation of enamides with a catalyst derived from monodentate phosphites and Rh(acac)(CO)₂ was studied. In the hydroformylation of N-vinylphthalimide, all the biphenol-based ligands led to the branched aldehyde; the fastest reaction was observed when using a sterically bulky phosphite. The olefins (E)-N-propenylphthalimide, vinylpyrrolidone, vinylcaprolactam and vinylcarbazole were also investigated.     

Preparation of enamides via palladium-catalyzed amidation of enol tosylates

[reaction: see text] A Pd-catalyzed coupling of enol tosylates and amides has been developed. Ligand screening revealed dipf as the most general ligand for this transformation. A variety of enol tosylates were coupled to an array of enamides in 58-97% yield.     

烯酰胺参与的不对称Povarov反应研究进展

烯酰胺因其氮活化的碳碳双键在各类含氮化合物的合成中具有潜在应用价值,其中有机催化的α,β-双官能化反应在有效骨架的构建中得到了广泛使用。烯酰胺参与的Povarov反应作为邻位双官能化反应的扩展应用,为4-氨基-1,2,3,4-四氢喹啉的构建提供一条简洁高效的途径。尽管该类反应如此重要,直到最近才开发出几种高效的不对称催化方案,本文将对这些研究进展进行总结。     

一锅法绿色合成烯酰胺和1,3-二炔(英文)

结合绿色化学概念,将酮肟还原酰化和末端炔氧化偶联在一锅进行反应,发展了一种Pd/Cu协同催化一锅绿色合成烯酰胺和1,3-二炔的新方法.该方法无需外加任何氧化剂和还原剂,可同时得到烯酰胺和1,3-二炔,产率高,反应条件温和.     

Highly enantioselective hydrogenation of N-phthaloyl enamides

Rh- or Ru-catalyzed highly enantioselective hydrogenation of N-phthaloyl enamides is presented. Electron-rich TangPhos and DuanPhos are found to be effective ligands for Rh-catalyzed hydrogenation of α-aryl enamides and up to 99% ee has been achieved. In contrast, for the hydrogenation of α-alkyl enamide, the Ru-C₃-TunePhos complex is more effective and up to 69% ee can be observed. This work is the first report of the hydrogenation of N-phthaloyl enamides.     

Chiral calcium organophosphate-catalyzed enantioselective electrophilic amination of enamides

Highly enantioselective direct amination of enamides catalyzed by chiral nonracemic calcium bis(phosphate) complex 3g afforded optically active 1,2-hydrazinoimines 4. Following a subsequent in situ hydrolysis or reduction, 2-hydrazinoketones 5 or syn-1,2-disubstituted 1,2-diamines 6 were obtained in high yields and excellent enantiomeric excess.     

A new preparation of enamides and dienamides.

α-Carbamido sulphones were anionized and alkylated ; basic elimination of the sulphonyl residue then led to enamides.