Kielesinski, Lukasz; Morawski, Olaf W.; Barboza, Cristina A.; Gryko, Daniel T. published an article in 2021. The article was titled 《Polarized Helical Coumarins: [1,5] Sigmatropic Rearrangement and Excited-State Intramolecular Proton Transfer》, and you may find the article in Journal of Organic Chemistry.Quality Control of 2,5-Dimethoxytetrahydrofuran The information in the text is summarized as follows:
The tandem process of phenol addition to a cyclic α,β-unsaturated ester followed by intramol. transesterification and [1,5] sigmatropic rearrangement affords a series of helical coumarins based upon a previously unknown 3-amino-7-hydroxybenzo[3,4]cyclohepta[1,2-c]chromen-6-one core. These novel polarized coumarins, possessing a β-ketoester moiety, have been employed to synthesize more rigid and helical coumarin-pyrazolones, which display green fluorescence. The enhanced emission of coumarin-pyrazolones in polar solvents depends on the nature of the S1 state. The coumarin-pyrazolones are predicted to have two vertical states close in energy: a weakly absorbing S1 (1LE) followed by a bright S2 state (1CT). In polar solvents, the 1CT can be stabilized below the 1LE and may become the fluorescent state. Solvatochromism of the fluorescence spectra confirms this theor. prediction. The presence of an N-H···O=C intramol. hydrogen bond in these coumarin-pyrazolone hybrids facilitates excited-state intramol. proton transfer (ESIPT). This process leads to a barrierless conical intersection with the ground electronic state and opens a radiationless deactivation channel effectively competing with fluorescence. Solvent stabilization of the CT state increases the barrier for ESIPT and decreases the efficiency of the nonradiative channel. This results in the observed correlation between solvatochromism and an increase of fluorescence intensity in polar solvents. In addition to this study using 2,5-Dimethoxytetrahydrofuran, there are many other studies that have used 2,5-Dimethoxytetrahydrofuran(cas: 696-59-3Quality Control of 2,5-Dimethoxytetrahydrofuran) was used in this study.
2,5-Dimethoxytetrahydrofuran(cas: 696-59-3) is a member of ether. Friedel Crafts reaction, for example, adds an alkyl or acyl group to aromatic ethers when they react with an alkyl or acyl halide in the presence of a Lewis acid as a catalyst.Quality Control of 2,5-Dimethoxytetrahydrofuran
Referemce:
Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem