Haizhen Jiang

C-9 Fluorenyl Substituted Anthracenes: A Promising New Family of Blue Luminescent Materials

Syntheses, optical, and electrochemical properties of novel C-9 fluorenyl substituted anthracenes linked by a tetrahedral sp(3)-hybridized carbon atom are reported for blue light emitting materials. Remarkably, an unoptimized organic light-emitting diode based on 1-fold fluorene-functionalized anthracene 3 exhibits a radiance of 4100 cd/m(2) at 12 V and a maximum EL efficiency of 1.36 cd/A with color purity CIE x, y (0.157, 0.082), which is very close to the National Television System Committee standard blue.

Enhancement of Neighbouring-Group Participation in Cu-0-Promoted Cross-Coupling gem-Difluoromethylenation of Aryl/Alkenyl Halides with 1,3-Azolic Difluoromethyl Bromides

A copper(0)-promoted direct reductive gem-difluoromethylenation of unactivated aryl or alkenyl halides with benzo-1,3-azolic (oxa-, thia- or aza-) difluoromethyl bromides or 2-bromodifluoromethyl-1,3-oxazoline has been developed for the construction of pharmaceutically important gem-difluoromethylene-linked twin molecules. The unique π-conjugated aryl-fused 1,3-azolic moiety in difluoromethyl bromide substrates could stabilise the reaction intermediates, which promotes the reactivities, providing facile access to the cross-coupling products in good to excellent yields, and allowing significant functional group tolerance. The reaction exhibits an enhanced neighbouring-group-participation effect. This method could provide a new strategy for the construction of gem-difluoromethylene-linked identical or nonidentical twin drugs through further functionalisation of 1,3-azolic skeletons.

Asymmetric aldol reaction organocatalyzed by bifunctional N-prolyl sulfinamides under solvent-free conditions

A class of chiral bifunctional N-prolyl sulfinamide and its TFA salts were prepared and proven to be effective for catalyzing the aldol reaction under solvent-free conditions. In general, the corresponding aldol adducts were obtained with high to excellent yields, and satisfactory diastereo-selectivities and enantioselectivities. A matching effect between chiral proline and sulfinamide moieties was observed in the catalysts. The enantioswitching of both enantiomers in the asymmetric aldol synthesis is found to be dominated by the prolyl moiety.

Nucleophile-Dependent Regioselective Reaction of (S)-4-Benzyl-2-Fluoroalkyl-1,3-Oxazolines

Nucleophile-dependent regioselectivities in the nucleophilic reaction of (S)-4-benzyl-2-fluoroalkyl-1,3-oxazoline to different types of fluorinated compounds were investigated experimentally and theoretically. The ring opening of (S)-4-benzyl-2-bromodifluoromethyl-1,3-oxazoline by arenethiolates exclusively occurred at the C5 position of the 1,3-oxazoline ring, whereas completely different regioselectivity was observed for a unimolecular radical nucleophilic substitution (S(RN)1) at the terminal bromine atom of the CF2Br group when arenolates were employed as the nucleophiles. The reaction of (S)-4-benzyl-2-trifluoromethyl-1,3-oxazoline with nucleophiles such as arenethiols, arenols, and TMSCl underwent nucleophilic ring opening in a regiospecific way, while the use of TMSCF3 was determined to proceed through nucleophilic addition to the C═N bond.

Ag-Initiated gem-Difluoromethylenation of the Nitrogen Center of Arenediazonium Salts to gem-Difluoromethylene Azo Compounds

An efficient method for the synthesis of the thermally stable and pharmaceutically important gem-difluoromethylene azo compounds is developed. This protocol achieved gem-difluoromethylenation of the nitrogen center of arenediazonium salts through in situ generated benzo-1,3-diazolic difluoromethylene radical addition to arenediazonium salts under mild Ag-initiated conditions.

Copper-catalyzed gem-difluoromethylenation of C(sp2)–H bonds of alkenes

Copper-catalyzed gem-difluoromethylenation of the C(sp2)–H bonds of alkenes with high functional group tolerance has been developed. This protocol is the first to efficiently achieve gem-difluoromethylenation of C(sp2)–H bonds of unactivated aliphatic terminal olefins and can be applied in a reaction cascade to achieve gem-difluoromethylenation/cyclization of alkenes.

Manganese-mediated/-catalyzed oxidative carboazidation of acrylamides

Manganese-mediated/-catalyzed oxidative carboazidation of acrylamides was developed for the synthesis of various azido oxindoles in 32% to 99% yields. tert-Butyl peroxybenzoate (TBPB) was used as an oxidant for the Mn-catalyzed method. And a Mn(II)/Mn(IV)/Mn(III) catalysis cycle via a stepwise or concerted regeneration of high-valent manganese was proposed for this protocol. This reaction system exhibits great functional group tolerance.

Synthesis and characterisation of nematic liquid crystals containing a trans‐decalin ring

The synthesis and mesomorphic behaviour of a series of liquid crystals incorporating a trans‐decalin ring and two aromatic rings linked by esters are reported. Structures of the new compounds were confirmed by IR, 1H NMR, 13C NMR and elemental analysis. A single crystal of compound 18 was prepared to confirm the trans‐conformation of the decalin ring. Liquid crystalline properties were investigated by differential scanning calorimetry and polarising optical microscopy. All of the synthesised compounds except 17e are found to show only an enantiotropic nematic phase over a wide temperature range.

A facile total synthesis of drospirenone isomers containing 14β-hydrogen configuration.

A facile strategy for the preparation of two isomeric drospirenones 13 and 16 possessing a 14β-hydrogen was developed, using 3β-hydroxyandrost-5-en-17-one as the starting material. The total synthetic route involves eight steps, giving 2% overall yield. The structures of the main compounds 11, 13, 14 and 16 were determined by single crystal XRD analysis.

Ethyl 2-phenyl-5-trifluoro­methyl-1,3-thia­zole-4-carboxyl­ate

In the title compound, C13H10F3NO2S, the dihedral angle between the thiazole and phenyl rings is 5.15 (1)°. No intermolecular hydrogen bonding is observed in the crystal structure.