6039-97-0Relevant academic research and scientific papers
Schwartz reagent mediated synthesis of thiazolones and imidazolones from thiazolidine-2,4-diones and imidazolidine-2,4-diones
Dandepally, Srinivasa Reddy,Elgoummadi, Radouane,Williams, Alfred L.
, p. 925 - 928 (2013/02/25)
A novel reduction/elimination method of thiazolidine-2,4-dione and imidazolidine-2,4-dione derivatives using Schwartz reagent to synthesize numerous thiazolones and imidazolones in a single step is reported.
New heterocyclic inputs for the povarov multicomponent reaction
Vicente-Garcia, Esther,Ramon, Rosario,Lavilla, Rodolfo
supporting information; experimental part, p. 2237 - 2246 (2011/09/15)
Oxa-, thia- and imidazolones are reactive inputs as electron-rich olefin components in Povarov reactions. On interaction with anilines and aldehydes, these substrates afford the corresponding multicomponent adducts in a regioselective manner. Intramolecular processes are also explored. Post-condensation oxidation provides convenient access to a variety of fused quinoline derivatives. Georg Thieme Verlag Stuttgart ? New York.
The Mechanism of Thermal Eliminations. Part 21. Rate Data for Pyrolysis of 2-Ethoxyquinoline, 1-and 3-Ethoxyisoquinoline, and 1-Ethoxythiazole: Correlation of Reactivities with ?-Bond Order of the C=N Bond
Al-Awadi, Nouria,Taylor, Roger
, p. 1589 - 1592 (2007/10/02)
We have measured the rates of thermal elimination of ethylene from the title compounds between 587.3 and 722.9 K.The reactivities relative to 2-ethoxypyridine at 650 K are: 3-ethoxyisoquinoline (0.21), 2-ethoxyquinoline (3.13), 1-ethoxyisoquinoline (6.47), 2-ethoxythiazole (63.1).These reactivities parallel the ?-bond order of the C=N bond, though the exceptional reactivity of 2-ethoxythiazole is attributed to additional acceleration through +M electron release from sulphur to nitrogen.This emphasizes the greater relative importance of nucleophilic attack by the nitrogen upon the β-hydrogen atom as compared with the analogous mechanism for pyrolysis of esters.Because of semi-concentrated nature of the reaction, interruption of aromaticity is much less significant than in, for example, electrophilic aromatic substitution.Thus retention of the benzenoid character of the ring not involved in the elimination is not an important rate-determining feature, as shown by the lower reactivity of 3-ethoxyisoquinoline relative to 2- ethoxypyridine.The unimportance of the interruption of aromaticity of the benzenoid ring means that conjugative effects are better relayed to nitrogen in the β-naphthalene-like position (isoquinoline) than in the α-naphthalene-like position (quinoline).This is the reverse of the familiar pattern for reactions of naphthalene-like systems where full charges are involved, and may be an additional factor contributing to the higher reactivity of 1-ethoxyisoquinoline than of 2-ethoxyquinoline, as may also be the -I effect of the benzo substiutent.The conclusions are used to predict elimination rates for alkoxyheterocycles not yet studied.
Stereoselective introduction of tetracyclines hydroxyl group at 12(a) position in synthesis of tetracyclines
-
, (2008/06/13)
In the synthesis of tetracyclines, a critical step is the stereospecific or stereoselective introduction of a hydroxyl group at the C-12(a) position, a novel method for the introduction of this critical hydroxy group is disclosed. Additionally, synthetic procedures for obtaining tetracycline precursors are discussed.
