51789-92-5Relevant articles and documents
Rate acceleration and subsequent retardation of Diels-Alder reactions in LiClO4-diethyl ether: An experimental investigation
Kumar,Pawar
, p. 7646 - 7652 (2001)
The experimental kinetic data for several Diels - Alder reactions why a 5 M LiClO4-diethyl ether (LPDE) solution offers maximum enhancement of reaction rates, endo/exo ratios, and yields. These reactions, if carried out in LPDE solutions of concentrations higher than 5 M, show a substantial decrease in thse kinetic parameters. This decrease is attributed to the very high viscosity of LPDE solutions near saturation, though this interpretation is not consistent when considered in terms of sizes of the diene and dienophile. The monoetherates, dietherates, and higher other clusters in LPDE solutions and their relationship with the Lewis acid catalysis by Li+ offer a more plausible explanation of both enhancement and the decrease of the rate of Diels-Alder reactions in this medium.
Diels-Alder reaction of cyclopentadiene and alkyl acrylates in the presence of pyrrolidinium ionic liquids with various anions
Stefaniak, Waldemar,Janus, Ewa,Milchert, Eugeniusz
, p. 742 - 747 (2011)
The conversion and stereoselectivity of transformation to endo and exo norbornene derivatives was determined in the Diels-Alder reaction of cyclopentadiene with alkyl acrylates. The reactions were carried out in the pyrrolidinium ionic liquids in the presence of metal chlorides and trifluoromethanesulfonates as the catalysts. Shorter reaction times and higher conversions of dienophile were observed in a comparison with analogous cycloadditions carried out in the presence of conventional organic solvents. A higher stereoselectivity to the endo isomer was found in the majority of cases. The ionic liquids composed of 1-butyl-1-methylpyrrolidinium cation (Pyrr 1.4) and various anions were used. The influence of ionic liquid anion and several metal chlorides and metal triflates used as the catalysts on the conversion was determined. Graphical Abstract: The conversion and stereoselectivity of transformation to endo and exo norbornene derivatives was determined in the Diels-Alder reaction of cyclopentadiene with alkyl acrylates. The reactions were carried out in the pyrrolidinium ionic liquids in the presence of metal chlorides and trifluoromethanesulfonates as the catalysts. Shorter reaction times and higher conversions of dienophile were observed in a comparison with analogous cycloadditions carried out in the presence of conventional organic solvents. A higher stereoselectivity to the endo isomer was found in the majority of cases. The ionic liquids composed of 1-butyl-1-methylpyrrolidinium cation (Pyrr1.4) and various anions were used. The influence of ionic liquid anion and several metal chlorides and metal triflates used as the catalysts on the conversion was determined.
Synthesis and computational analysis of conformationally restricted [3.2.2]- and [3.2.1]-3-azabicyclic diamines
Tummalapalli, Sreedhar Reddy,Bhat, Rohit,Waitt, Craig,Eshuis, Henk,Rotella, David P.
, p. 4087 - 4089 (2017/10/06)
Conformational restriction is a useful approach for ligand design in organic and medicinal chemistry. This manuscript reports the facile synthesis and in silico conformational analysis of two new diastereomeric [3.2.2]-3-azabicyclic, two new [3.2.1]-3-aza-8-oxy-bicyclic and one new [3.2.1]-3-azabicyclic diamine scaffolds. A conformational analysis of these structures along with calculation of carbon–carbon/carbon–nitrogen bond angles was carried out and compared to those in the flexible 1,3-diaminopropane template upon which they were based. It is of particular importance that these scaffolds have bond lengths and angles that can overlap with low energy conformers of the flexible diamine. Such information is useful for ligand design in organic chemistry and for development of structure activity relationships and in silico screening in medicinal chemistry.
Liquid coordination complexes of Lewis acidic metal chlorides: Lewis acidity and insights into speciation
Hogg, James M.,Brown, Lucy C.,Matuszek, Karolina,Latos, Piotr,Chrobok, Anna,Swad?ba-Kwa?ny, Ma?gorzata
, p. 11561 - 11574 (2017/09/18)
Coordination complexes of Lewis acidic metal chlorides AlCl3, GaCl3, InCl3, SbCl3, SnCl4, SnCl2, ZnCl2 and TiCl4 with trioctylphosphine (P888) and trioctylphosphine oxide (P888O) were synthesised. All compounds formed liquid coordination complexes (LCCs) at ambient temperature, although decomposition via a redox mechanism was detected in some cases. The Lewis acidity of the metal chlorides (measured in 1,2-dichloroethane solutions) and the LCCs (measured neat) was quantified by using the Gutmann acceptor number (AN) approach. In general, LCCs were equally or more Lewis acidic than the corresponding metal chlorides. The AN values were compared with the catalytic activity of selected LCCs in a model Diels-Alder reaction. Insight into speciation of LCCs was gained using multinuclear NMR spectroscopy, revealing that most LCCs comprised charge-neutral complexes rather than ionic ones. The relationship between the speciation, Lewis acidity (AN scale) and catalytic activity is discussed in detail. This approach reveals several new, promising catalytic systems, such as P888O-InCl3, with Lewis acidity enhanced compared to chloroindate ionic liquids, and P888O-TiCl4, with hydrolytic stability enhanced with respect to neat TiCl4.
