Reactions of Acetals With Unsaturated Ethers

Abstract

A brief review of established methods shows that only with the Berthelot technique is it possible to see a finite volume of liquid in sustained mechanical tension. A short discussion of the practice and theory reveals two uncertainties with the conventional technique : that of the determination of a true filling temperature, and the influence of compliance by the glass on the tension developed. A description is then given of a modified apparatus with which these difficulties do not arise. The tube is formed into a coil which deflects sufficiently to indicate internal pressure or tension, and by monitoring these deflections with a distance meter a record of pressure/ tension against temperature can be made. The course of a typical run is shown from which the excess pressure, filling temperature and limiting tension may all be estimated with much greater precision than befoie. The orders of magnitude of the results obtained are indicated, and a possible influence of non-uniform gaseous supersaturation is suggested.

Lewis Acid-Catalyzed Additions of (Benzotriazol-1-yl)diethoxymethane to Enol Ethers and Enamides. New Syntheses of β-Alkoxyalkanal and β-Aminoalkanal Acetals

“…An advantage of our new methodology is that the acetals 13 are inactive toward competitive addition to enol ethers: in all the cases we used acetal and vinyl ether in equimolar ratio and did not observe the formation of any secondary addition products, while previously described reactions of stoichiometric amounts of acetals and enol ethers led to the formation of oligomers. , This difference in the reactivity patterns in acetals and 11 becomes crucial as far as their reactions with cyclic enol ethers are concerned. Substituted tetrahydrofurans and tetrahydropyrans are the structural subunits in naturally occurring polyether antibiotics, pheromones, etc . , Additions of acetals to dihydrofurans and dihydropyrans were previously found to yield the corresponding 2-alkoxy-3-(α-alkoxy)alkyltetrahydrofurans or -pyrans; 5,12,13 however, these reactions are often complicated by the formation of secondary condensation products.…”

“…The crude products contained small amounts (5−9%) of ethers 14a − c , as shown by NMR spectra . The formation of the byproduct ethers 14 is explained by the addition to the double bond of vinyl ether of free benzotriazole which generated by reaction of ethanol with 11 , the ethanol being formed by elimination from 13a − c (compare with formation of vinyl ethers from diacetals , ). Compounds 13a − c were separated by column chromatography and were characterized by NMR spectroscopy.…”

Solvent‐Free Synthesis of New Quinoline Derivatives via Eaton's Reagent Catalysed Friedländer Synthesis

“…General procedure for synthesis and copies of 1 H, 13 C, 2D NMR and HR-MS spectral data of the synthesized compounds associated with this article will be available as supporting information.…”

“…[1][2][3][4][5][6][7] Several classical methods to synthesize quinoline core have been reported, the Skraup, [8] Doebner von Miller, [9] Pfitzinger, [10] Conrad-Limpach, [11] Combes syntheses [12] and Povarov reaction. [13] Among them, the Friedländer synthesis is still accessed by researchers as a recognized approach for the synthesis of quinoline analogues in the heterocyclic chemistry from 1882. [14,15] Friedländer synthesis was developed by researchers to prepare quinoline derivatives by condensation of easily accessible 2-aminoarylketones with carbonyl compounds attaining a reactive methylene group cum cyclodehydration, [16][17][18][19] in recent scenario this method is focused immense output using various catalyst and methodology, such as Bronsted acids, Lewis acids, greener methods, nano catalysts, ionic liquids and using various solvents.…”

Photocatalytic Synthesis of Quinolines via Povarov Reaction under Oxidant-Free Conditions

“…Subsequently, the formed tetrahydroquinolines undergo oxidation into quinolines. 16,17 The oxidation step involves formal removal of four hydrogen atoms from a tetrahydroquinoline nucleus. Typically, harsh conditions and stoichiometric amounts of oxidants such as peroxides, high-valent metals, tetramethylpiperidinyloxy (TEMPO) oxoammonium salts, and iodine(III) oxidants are employed.…”