Enantiospecific Generation and Trapping Reactions of Aryne Atropisomers.

Enantioenriched aryne atropisomers having a biaryl stereogenic axis vicinal to the reactive triple bond are demonstrated to exist. These reaction intermediates are easily produced in situ and can undergo the standard aryne cycloaddition chemistry in an enantiospecific manner. Notably, the aryne atropisomers herein have allowed the practical syntheses of a small nanographene as well as some triptycene and anthracene derivatives that embed stereogenic axes of controlled absolute configurations.

Synthesis of indolo[2,1-a]isoquinoline derivatives via visible-light-induced radical cascade cyclization reactions.

We describe a photocatalyzed transformation for the synthesis of the indolo[2,1-a]isoquinoline core structure. This redox neutral reaction features mild reaction conditions and exceptional functional group tolerance. A series of valuable indolo[2,1-a]isoquinoline derivatives bearing various functional groups were synthesized using this method in good to excellent yields.

Enantioselective Organocatalytic Four-Atom Ring Expansion of Cyclobutanones: Synthesis of Benzazocinones.

An enantioselective Michael addition- four-atom ring expansion cascade reaction involving cyclobutanones activated by a N-aryl secondary amide group and ortho-amino nitrostyrenes has been developed for the preparation of functionalized eight-membered benzolactams using bifunctional aminocatalysts. Taking advantage of the secondary amide activating group, the eight-membered cyclic products could be further rearranged into their six-membered isomers having a glutarimide core under base catalysis conditions without erosion of optical purity, featuring an overall ring expansion- ring contraction strategy.

Alkene functionalization for the stereospecific synthesis of substituted aziridines by visible-light photoredox catalysis.

A novel strategy involving visible-light-induced functionalization of alkenes for the synthesis of substituted aziridines was developed. The readily prepared N-protected 1-aminopyridinium salts were used for the generation of N-centered radicals. This approach allowed the synthesis of aziridines bearing various functional groups with excellent diastereoselectivity under mild conditions. Moreover, this protocol was successfully applied to prepare structurally diverse nitrogen-containing frameworks.

Chemical characteristics of the fungus Ganoderma lucidum and their inhibitory effects on acetylcholinesterase.

The chemical characteristic of a well-known folk medicine Ganoderma lucidum has been investigated by a series of chromatographic technologies, which displayed the presences of 45 lanostane type triterpenoids, including two new nor-lanostane triterpenoids (40, 41). Their structures were identified on the basis of spectroscopic data analysis (UV, IR, HRESIMS, 1D, and 2D NMR). Notably, some triterpenoids displayed moderate inhibitory effects against AChE (acetylcholinesterase) by an in vitro screened experiment. Triterpenoid 2 displayed the potent inhibitory effect with IC50 10.8 and Ki 14.95 µM (inhibition kinetic). The preliminary SAR has been discussed by the docking analyses between ganoderic acids (1, 2) and AChE.

Diterpenoids from the roots of Euphorbia fischeriana and their inhibitory effects on α-glucosidase.

Chemical investigation has been performed on the roots of Euphorbia fischeriana, a traditional Chinese medicine. Three diterpenoids were obtained using various chromatographic techniques, and their structures were determined by spectroscopic data including HRESIMS, 1D NMR, 2D NMR, ECD, and calculated ECD, which gave two new diterpenoids, daphnane type (1) and ent-pimarene type (3). Additionally, the isolated compounds (1-3) displayed moderate inhibitory effects against α-glucosidase in an in vitro bioassay.

Direct Decarboxylative-Decarbonylative Alkylation of α-Oxo Acids with Electrophilic Olefins via Visible-Light Photoredox Catalysis.

The decarbonylation of primary, secondary, and tertiary alkyl-substituted acyl radicals has been investigated through photoredox catalysis. A series of quaternary carbons and γ-ketoesters have been directly constructed by the photoredox 1,4-conjugate addition of the corresponding alkyl ketoacids with electrophilic alkenes. And, the tertiary alkyl ketoacids have proved to be good precursors of tertiary alkyl radicals.

Photoredox-Induced Functionalization of Alkenes for the Synthesis of Substituted Imidazolines and Oxazolidines.

A one-pot, three-component cascade reaction combining photoredox catalyzed radical addition and formal [3 + 2] annulation was developed. With this approach, highly concise syntheses of imidazoline and oxazolidine derivatives have been achieved. The advantages of this transformation are good to excellent yields, mild reaction conditions, operational simplicity, and easy accessibility of raw materials.

Intramolecular 1,5-H transfer reaction of aryl iodides through visible-light photoredox catalysis: a concise method for the synthesis of natural product scaffolds.

The intramolecular 1,5-H transfer reaction of the aryl radicals generated from unactivated aryl iodides by photocatalysis is described. The features of this transformation are operational simplicity, excellent yields, mild reaction conditions, and good functional group tolerance. With this approach, a more concise formal synthesis of (±)-coerulescine and (±)-physovenine is accomplished.

[A comparison between the eye trackers of laser cornea correction systems made by foreign manufacturers].

Photo refractive keratectomy (PRK) and laser Situ Keratomileusis (LASIK) have been used for over a decade and become popular in China. Principles and characteristics of eye trackers made by several famous foreign manufacturers are introduced in this paper and their developing direction in the future is pointed out too.