Enantioselective nickel-catalyzed dicarbofunctionalization of 3,3,3-trifluoropropene.

Despite paramount applications of chiral trifluoromethylated compounds in medicinal chemistry and materials science, limited strategies have been developed for catalytic asymmetric synthesis of such valuable fluorinated structures. Here, we report a nickel catalyzed enantioselective dicarbofunctionalization of inexpensive industrial chemical 3,3,3-trifluoropropene (TFP) with readily available tertiary alkyl and aryl iodides. The reaction overcomes the ß-F elimination side reaction of TFP, and proceeds efficiently under mild reaction conditions. The protocol possesses advantages, such as synthetic convenience, high enantioselectivity, and excellent functional group tolerance, providing rapid and straightforward access to chiral trifluoromethylated compounds of medicinal interest.

Fe-BPsalan Complex-Catalyzed Asymmetric [4 + 2] Cycloaddition of Cyclopentadiene with α,ß-Unsaturated Heterocycles.

An efficient iron-catalyzed asymmetric [4 + 2] cycloaddition of cyclopentadiene with α,ß-unsaturated acyl imidazoles or 2-cinnamoylisoindoline-1,3-dione derivatives was developed to afford the addition products in high yield and selectivity. Interestingly, the absolute structures of the addition products were controlled by the auxiliaries via different coordination modes with the same type of catalyst.

Regio- and enantioselective umpolung gem-difluoroallylation of hydrazones via palladium catalysis enabled by N-heterocyclic carbene ligand.

The enantioselective construction of C-CF2R (R: alkyl or fluoroalkyl) bonds has attracted the attention of synthetic chemists because of the importance of chiral fluorinated compounds in life and materials sciences. Catalytic asymmetric fluoroalkylation has mainly been realized under organocatalysis and Lewis acid catalysis, with substrates limited to carbonyl compounds. Few examples using transition-metal catalysis exist, owing to side reactions including decomposition and isomerization of fluoroalkylating reagents. Herein we report umpolung asymmetric difluoroallylation of hydrazones with 3-bromo-3,3-difluoropropene (BDFP) under palladium catalysis. Difluoroallylation products having quaternary chiral carbon centers are afforded in good yields with high α/γ- and enantioselectivities. The usefulness of the reaction products is demonstrated and an inner-sphere mechanism of the reaction is proposed. The use of chiral N-heterocyclic carbene as ligand is the key for the selectivities as well as the productivity of the reaction.

Successful endoscopic treatment of an intestinal diospyrobezoar migrated from the stomach.

Diospyrobezoars are a rare cause of small intestinal obstruction. A 78-year-old man, with a history of persimmons ingestion and gastrectomy, presented with upper abdominal pain and weight loss. The upper gastrointestinal endoscopy showed a huge bezoar in the stomach. After initial endoscopic fragmentation, the abdominal X-ray revealed intestinal obstruction and the colonoscopy showed large fragments of the bezoar filling the terminal ileum. The migrated bezoar pieces were successfully removed by endoscopic fragmentation with a cutting lithotripter.

Enantioselective Pd-catalyzed allylation of acyclic α-fluorinated ketones.

Significant synthetic challenges remain for the asymmetric synthesis of tertiary α-fluoro ketones, which are potentially useful molecules for the development of drugs, agrochemicals, and functional materials. Herein, we describe the development of a method for the catalytic enantioselective synthesis of tertiary α-fluoro ketones via the Tsuji-Trost reaction of racemic acyclic α-fluorinated ketones. Enantioenriched acyclic α-cabonyl tertiary fluorides can be produced with the aid of a palladium/phosphinooxazoline catalyst.

Highly enantioselective intermolecular carbene insertion to C-H and Si-H bonds catalyzed by a chiral iridium(III) complex of a D4-symmetric Halterman porphyrin ligand.

The chiral iridium porphyrin [Ir((-)-D(4)-Por*)(Me)(EtOH)] displays excellent reactivity and stereoselectivity towards carbene insertion to C-H and Si-H bonds, affording corresponding products in high yields (up to 96%) and high enantioselectivities (up to 98% ee).

Kinetic resolution of 2,3-dihydro-2-substituted 4-quinolones by palladium-catalyzed asymmetric allylic alkylation.

The kinetic resolution of a carbon nucleophile is realized for the first time via Pd-catalyzed asymmetric allylic alkylation with "unstabilized" ketone enolates as the nucleophile, providing both allylated 2,3-disubstituted 2,3-dihydro-4-quinolones and recovered substrates in high yields and high ee (S-factor is 40-145). The application of the methodology in organic synthesis is demonstrated by the ready transformation of an allylated adduct into pyrrolo[3,2-c]quinoline, which features a core structure of biologically active Martinella alkaloids.

Highly diastereo- and enantioselective Pd-catalyzed cyclopropanation of acyclic amides with substituted allyl carbonates.

A highly diastereo- and enantioselective cyclopropanation reaction was realized in the reaction of acyclic amides with monosubstituted allyl carbonates via Pd-catalysis using a ferrocene ligand with H as a substituent on an oxazoline ring, providing cyclopropane products having three chiral centers in yields of 67-83%, the dr ratio being 4-23:1, and ee being 83-97%. The presence of LiCl is important for the gain of high diastereo- and enantioselectivities of the reaction.

Effects of motilin and ursodeoxycholic acid on gastrointestinal myoelectric activity of different origins in fasted rats.

AIM: To investigate gastrointestinal migrating myoelectric complex (MMC) and the effects of porcine motilin and ursodeoxycholic acid (UDCA) on MMC of gastrointestinal tract of different origins in fasted rats. METHODS: Three bipolar silver electrodes were chronically implanted on the antrum, duodenum and jejunum. Seven days later 24 experimental rats were divided into 2 groups. One group was injected with porcine motilin via sublingual vein at a dose of 20 microg/kg, the other group was perfused into stomach with UDCA. The gastrointestinal myoelectric activity was recorded 1 h before and 2 h after the test substance infusions into the rats. RESULTS: In all fasted rats a typical pattern of MMC was observed. Among the totally 68 activity fronts recorded in fasted rats under control, 67% started in duodenum, and 33% in antrum. MMC cycle duration and duration of phase III of antral origin were longer than those of duodenal origin. Administration of 20 microg/kg porcine motilin induced a premature antral phase III of antral origin. But perfusion into stomach with UDCA resulted in shorter MMC cycle duration, longer duration of phase III of duodenal origin, which were followed with shorter cycle duration and duration of antral phase III. CONCLUSION: In fasted rats, MMC could originate from antrum and duodenum respectively. The characteristics of MMC of different origins may contribute to the large variations within subjects. The mechanisms of different origins of phase III may be different. Porcine motilin and UDCA could affect MMC of different origins of the gastrointestinal tract in fasted state, respectively.