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
Palladium‐Catalyzed
<i>peri</i>
‐Selective C−H Fluoroalkoxylation of Aryl Sulfoxides
作者:Tomohiko Sato、Keisuke Nogi、Hideki Yorimitsu
DOI:10.1002/cctc.202000485
日期:2020.7.6
Sulfinyl‐directed peri‐selective C−H fluoroalkoxylation of arylsulfoxides with fluorinated alcohols has been developed. By means of a palladium catalyst and PhI(OAc)2 as an oxidant, a range of fluoroalkoxy groups can be installed onto the peri position of arylsulfoxides. The remaining sulfinyl groups on the fluoroalkoxylation products further promote Pummerer‐based C−H functionalizations.
A regioselective C–H sulfanylation of aryl sulfoxides with alkylaryl sulfides in the presence of acid anhydride was developed, which resulted in the formation of 1,4-disulfanylarenes after dealkylation of initially formed sulfonium salts. The reaction began with Pummerer-type activation of aryl sulfoxides followed by nucleophilic attack of alkylaryl sulfides. The nucleophilic attack occurred exclusively
C−H iodination of aromatic compounds has been accomplished with the aid of sulfinyl directing groups under palladium catalysis. The reaction proceeds selectively at the peri‐position of polycyclic aryl sulfoxides or at the ortho‐position of phenyl sulfoxides. The iodination products can be further converted via iterative catalytic cross‐coupling at the expense of the C−I and C−S bonds. Computational