Wujiong Xia

Reactivity Insight into Reductive Coupling and Aldol Cyclization of Chalcones by Visible Light Photocatalysis

The reductive coupling and cyclization of chalcones to generate cyclopentanol derivatives in up to 84% yield by visible light photoredox catalysis is described. This reaction involves radical anion homocoupling, monoprotonation, and intramolecular cyclization cascade.

Visible-Light-Promoted Direct Amination of Phenols via Oxidative Cross-Dehydrogenative Coupling Reaction

A transition-metal-free approach was disclosed for intermolecular aryl C-N bonds formation between phenols and cyclic anilines via cross-dehydrogenative coupling (CDC) amination that was mediated by visible light, wherein K2S2O8 served as an external oxidant. The salient features of this protocol include circumventing the requirement for prefunctionalized starting materials and achieving single regioselectivity of amination adducts at room temperature.

Efficient synthesis of polysubstituted isochromanones via a novel photochemical rearrangement.

A novel and convenient approach to the synthesis of polysubstituted isochromanones is described. Irradiation of 2-formyl phenylalkeno-derivatives with UV light in benzene solution afforded the corresponding products in up to 98% yield. The possible reaction mechanism is proposed and further supported by the isotopic experiments.

Visible-light photoredox catalysis enabled bromination of phenols and alkenes

Summary A mild and efficient methodology for the bromination of phenols and alkenes has been developed utilizing visible light-induced photoredox catalysis. The bromine was generated in situ from the oxidation of Br− by Ru(bpy)3 3+, both of which resulted from the oxidative quenching process.

Application of chiral N-tert-butylsulfinyl vinyl aziridines in Rh(I) catalyzed 1,4-addition of aryl boronic acids to cyclic enones

Chiral N-tert-butylsulfinyl vinyl aziridine ligands prepared from a readily available (R)-tert-butanesulfinamide have been applied in the rhodium-catalyzed asymmetric 1,4-addition of aryl boronic acids to cyclic enones, which gives high yields and excellent enantioselectivities.

Bioactive selaginellins from Selaginella tamariscina (Beauv.) Spring

Summary A new selaginellin named selaginellin O (1), along with three other known selaginellins (2–4) were isolated from Selaginella tamariscina (Beauv.) Spring. On the basis of spectroscopic analysis, the structure of selaginellin O was demonstrated to be 4-[(4’-hydroxy-4-formyl-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene]cyclohexa-2,5-dien-1-one. Compound 1, 2 and 3 exhibited appreciable cytotoxic activity against cultured HeLa cells (human cervical carcinoma cells), as well as significant antioxidant activity.

Solid-state asymmetric photochemical studies using the ionic chiral auxiliary approach.

The ionic chiral auxiliary approach to asymmetric photochemical synthesis discovered by the Scheffer group has been successfully applied to many reactions in the solid state. Enantiomeric excesses of up to 99% were obtained using this method. After a brief introduction of absolute asymmetric synthesis, chirally modified zeolites and host-guest assemblies in asymmetric photochemistry, the bulk of this review will summarize and discuss the application of the solid state ionic chiral auxiliary technique to the Norrish type II reaction, the di-pi-methane photorearrangement, and to a novel retro-Claisen photorearrangement.

Photochemical studies on aromatic γ,δ-epoxy ketones: efficient synthesis of benzocyclobutanones and indanones

Irradiation of terminal aromatic γ,δ-epoxy ketones with a 450 W UV lamp led to Norrish type II cyclization/semi-pinacol rearrangement cascade reaction which formed the benzocyclobutanones containing a full-carbon quaternary center, whereas irradiation of substituted aromatic γ,δ-epoxy ketones led to the indanones through a photochemical epoxy rearrangement and 1,5-biradicals cyclization tandem reaction.

Influence of the steric hindrance of organic amines on the supramolecular network based on polyoxovanadates

Three new supramolecular architectures based on polyoxovanadates H6V10O28·2HMTA·8H2O(1), [Ni(enMe)3]2(VIV8VV7O36Cl)·2H3O (2) and [Co(en)3]2(VIV8VV7O36Cl)·2H3O (3) (HMTA = hexamethylenetetramine, enMe = 1,2′-propanediamine and en = ethylenediamine) have been prepared and characterized by elemental analyses, IR spectra, XPS spectra and single crystal X-ray diffraction structure analyses. Compound 1 displays a 3-D (4,8)-connected supramolecular host network, which is constructed of octamer water clusters and HMTA molecules, with 1-D channels occupied by the template [H6V10O28] units. Compound 2 possesses a 2-D (3,6)-connected supramolecular layered structure formed by water molecules and [V15O36]3− units showing honeycomb cavities occupied by the transition metal complexes (TMCs). Compound 3 exhibits a 3-D (4,6)-connected supramolecular host network built by the [V15O36]3− units and the lattice water molecules with TMCs cations as the template. By a careful inspection of the structures of 1–3, it is believed that the steric hindrances of organonitrogen ligands are important for the formation of different supramolecular networks. Compound 1 exhibits intensive photoluminescence and compound 3 displays antiferromagnetic interactions.

pH-dependent assembly of a series of inorganic–organic hybrid molybdenum(v) phosphate

Four inorganic–organic hybrid materials based on poly(oxomolybdophosphate) cluster building blocks have been obtained by hydrothermal methods. 1 shows a 2-D sheet structure, 2 and 3 possess 1-D chain structures and 4 is the discrete cluster. Crystal structural analysis reveals that the dimensionality and organization of those compounds can be tuned by the pH value of the reaction system. In addition, the fluorescence emissions are analysed of compounds 1, 2 and 4 containing Cd atoms with d10 electronic configuration red-shift along with the increase in the dimensions of those compounds.