Photophysics and Photostereomutation of Aryl Methyl Sulfoxides1
摘要:
The effect of a methanesulfinyl group on the photophysics of several aromatic chromophores is reported. The spectroscopic singlet and triplet energies are affected only modestly, compared to that parent arenes, but the fluorescence yields fall by at least 1 order of magnitude. Fluorescence lifetimes are short. Fluorescence enhancements are observed on cooling the sulfoxides from room temperature to 77 K. High quantum yields of stereomutation are reduced as the temperature drops. There is not a consistent effect on triplet or phosphorescence yields. It is proposed that these results are consistent with a nonradiative pathway for deactivation of the singlet that results in stereomutation. A modest activation energy of a few kcal/mol is estimated for the photochemical racemization of 1-methanesulfinylpyrene
Inherent vs Apparent Chemoselectivity in the Kumada–Corriu Cross-Coupling Reaction
作者:XiYe Hua、Jeanne Masson-Makdissi、Ryan J. Sullivan、Stephen G. Newman
DOI:10.1021/acs.orglett.6b02631
日期:2016.10.21
The Kumada–Corriu reaction is a powerful tool for C–C bond formation, but is seldom utilized due to perceived chemoselectivity issues. Herein, we demonstrate that high-yielding couplings can occur in the presence of many electrophilic and heterocyclic functional groups. Our strategy is mechanically based, matching oxidative addition rates with the rate of syringe pump addition of the Grignard reagent
A family of simple amide-derived air-stable P,O-ligands for Suzuki cross-coupling of unactivated aryl chlorides
作者:Wei-Min Dai、Ye Zhang
DOI:10.1016/j.tetlet.2004.12.133
日期:2005.2
variations, as hemilabile bidentate P,O-ligands in various Pd-catalyzed C–N and C–C bond forming reactions. We present here our results on the highly efficient Suzukicross-coupling reactions of unactivated and/or sterically hindered aryl chlorides with arylboronic acids and a relationship of Aphos structures with catalytic efficacy.
A method for preparing a polymer is provided. The method for preparing a polymer includes subjecting at least one monomer having a structure represented by Formula (I) to a reaction in the presence of sulfonic acid, diphenyl amine, and oxygen-containing phosphide, obtaining a sulfonium salt polymer
, wherein x is 0, 1, or 2; R1 is C1-6 alkyl group; and R2 is independently hydrogen, or C1-6 alkyl group.
A method for preparing a polymer is provided. The method for preparing a polymer includes subjecting at least one monomer having a structure represented by Formula (I) to a reaction in the presence of sulfonic acid, diphenyl amine, and oxygen-containing phosphide, obtaining a sulfonium salt polymer
wherein x is 0, 1, or 2; R1 is C1-6 alkyl group; and R2 is independently hydrogen, or C1-6 alkyl group. In particular, the molar ratio of the diphenyl amine to the oxygen-containing phosphide is from 4:1 to 1:1.