Lanthanide Triflate Catalyzed Imino Diels-Alder Reactions; Convenient Syntheses of Pyridine and Quinoline Derivatives
作者:Shū Kobayashi、Haruro Ishitani、Satoshi Nagayama
DOI:10.1055/s-1995-4066
日期:1995.9
Lanthanide triflate catalyzed imino Diels-Alder reactions of imines with dienes or alkenes have been developed. A new group of Lewis acids, lanthanide triflates, are quite effective for the catalytic activation of imines. Unique reactivities of imines which work as both dienophiles and azadienes under certain conditions have been revealed. Three-component coupling reactions between aldehydes, amines, and dienes or alkenes were successfully carried out by using lanthanide triflate as a catalyst to afford pyridine and quinoline derivatives in high yields. The Lewis acid catalysts were stable and kept their activity even in the presence of water and amines. A stepwise reaction mechanism for these reactions is suggested from the experimental results.
Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction
作者:Jie Yu、Hua-Jie Jiang、Ya Zhou、Shi-Wei Luo、Liu-Zhu Gong
DOI:10.1002/anie.201504790
日期:2015.9.14
The sodium salts of anionic chiral cobalt(III) complexes (CCC−Na+) have been found to be efficient catalysts of the asymmetric Povarov reaction of easily accessible dienophiles, such as 2,3‐dihydrofuran, ethyl vinyl ether, and an N‐protected 2,3‐dihydropyrrole, with 2‐azadienes. Ring‐fused tetrahydroquinolines with up to three contiguous stereogenic centers were thus obtained in high yields, excellent
[reaction: see text] (R,R)-3-Aza-3-benzyl-1,5-dihydroxy-1,5-diphenylpentane (1) ligated Ti(IV) complex (1-TiCl(2)) is used as a chiral Lewis acid catalyst for promoting asymmetric IED Diels-Alder reaction between electron-rich dienophiles and electron-poor dienes. Here we introduce a facileroute for the synthesis of asymmetric tetrahydroquinoline derivatives using the above-mentioned chiral catalyst
New Findings on the Cerium(IV) Ammonium Nitrate Catalyzed Povarov Reaction: Stereoselective Synthesis of 4-Alkoxy-2-aryl-1,2,3,4-tetrahydroquinoline Derivatives
Cerium(IV) ammonium nitrate catalyzes the three-component, imino Diels-Alder (Povarov) reaction between anilines, aromatic aldehydes, and acyclic vinyl ethers, giving cis-4-alkoxy-2-aryl-1,2,3,4-tetrahydroquinolines with almost complete diastereoselectivity. The corresponding reaction starting from cyclic vinyl ethers gave the two possible diastereomers, with the endo-compound as the major product. This stereochemical outcome is explained through a stepwise mechanism for the imino Diels-Alder reaction, and this mechanism was subsequently proved by trapping the putative oxonium intermediate in the presence of ethanol.
of imine (generated in situ from aromatic amine and aldehyde) with dienophile in acetonitrile in a diastereoselective manner. The use of water as solvent reverses the diastereoselectivity toward the cis isomer. Interestingly, tricyclic pyrano/furano benzopyran with cis diastereoselectivity is obtained when salicylaldehyde is used as an alternative of aromaticaldehyde under the same condition. These