Fluorescence Sensing of Glutathione Thiyl Radical by BODIPY-Modified β-Cyclodextrin

Comprehensive Summary The fluorescence sensing of intracellular glutathione thiyl radical(GS·)is in great demand to seek the GS·-related pathophysiological events.Herein,boron-dipyrromethene(BODIPY)-modified β-cyclodextrin was developed for high-efficiency sensing of GS·,accompanied by a fast response time(t_(1/2)=218 s),with the detection limit of 468 nmol/L.Cell experiments indicated that the BODIPY-modified p-cyclodextrin could be applied to detect the GS· in live A549 cells.

Photoredox Synthesis of Thio-Functionalized Cyclic Ethers Using N-Sulfenyl Phthalimides as a Thiyl-Radical Precursor

Comprehensive Summary A visible-light mediated exclusively regioselective synthesis of 2,2-disubstituted thio-functionalized tetrahydrofurans,tetrahydro-pyrans and oxepanes has been described through an operationally simple and mild photoredox protocol.Thiyl radical generated from N-phenylsulfenyl phthalimide by photoredox catalysis was proven to be the key reactive intermediate in this reaction.

Radicals as Chiral Catalysts for Asymmetric Radical Cyclization Reactions

Due to the innate highly reactive properties and short life-time,organic free radicals can often serve as promoters or intermediates to engage in various radical transformations,which are often otherwise difficult to access by ionic pathway-based mechanisms.With the evolvement of radical chemistry,chiral radical catalyzed-transformations have recently emerged as an attractive and robust platform for synthesis of chiral molecules of interest.Herein,we highlight several creative and strategic advances in chiral radical catalyst design,cyclization reaction achievements,and future challenges.

α-Substituent Effects on Si--H, P- H and S--H Bond Dissociation Energies

CBS-Q and G3 methods were used to generate a large number of reliable Si--H, P---H and S--H bond dissociation energies （BDEs） for the first time. It was found that the Si--H BDE displayed dramatically different substituent effects compared with the C--H BDE. On the other hand, the P---H and S--H BDE exhibited patterns of substituent effects similar to those of the N--H and O--H BDE. Further analysis indicated that increasing the positive charge on Si of XSiH3 would strengthen the Si--H bond whereas increasing the positive charge on P and S of XPH2 and XSH would weaken the P---H and S--H bonds. Meanwhile, increasing the positive charge on Si of XSiH2^＋ stabilized the silyl radical whereas increasing the positive charge on P and S in XPH＂ and XS＊ destabilized P- and S-centered radicals. These behaviors could be reasonalized by the fact that Si is less electronegative than H while P and S are not. Finally, it was demonstrated that the spin-delocalization effect was valid for the Si-, P- and S-centered radicals.