15679-19-3Relevant articles and documents
Cs2CO3-Promoted C?O Coupling Protocol Enables Solventless (Hetero)aryl Ether Synthesis under Air Atmosphere
Jiang, Bowen,Chen, Cheng,Fan, Guang-Gao,Sang, Wei,Cheng, Hua,Zhang, Rui,Yuan, Ye,Li, Qi-Zhong,Verpoort, Francis
supporting information, (2022/02/05)
In this work, a Cs2CO3-promoted synthetic approach was identified for (hetero)aryl ether synthesis via the C?O coupling of various (hetero)aryl chlorides and alcohols/phenol. To our delight, the reactions could be carried out under transition-metal-free and solvent-free conditions. Moreover, analytical-grade reagents and air atmosphere were readily tolerated. To showcase the practical usefulness of the present protocol, the assembly of a bioactive molecule was facilely realized and the gram-scale production of selected ether products was also efficiently accomplished. In addition, density functional theory (DFT) studies, along with a few mechanistic experiments, were conducted to elucidate a proposed reaction pathway and rationalize the pivotal role of Cs2CO3 in promoting this process. Hopefully, this work could provide useful information for researchers who are engaging in C?O cross-coupling reactions.
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.
