Fangdong Hu

Rhodium(III)‐Catalyzed ortho Alkenylation of N‐Phenoxyacetamides with N‐Tosylhydrazones or Diazoesters through CH Activation

A coupling reaction of N-phenoxyacetamides with N-tosylhydrazones or diazoesters through Rh(III) -catalyzed CH activation is reported. In this reaction, ortho-alkenyl phenols were obtained in good yields and with excellent regio- and stereoselectivity. Rh-carbene migratory insertion is proposed as the key step in the reaction mechanism.

Rhodium(III)-Catalyzed Transannulation of Cyclopropenes with N-Phenoxyacetamides through CH Activation†

An efficient rhodium(III)-catalyzed synthesis of 2H-chromene from N-phenoxyacetamides and cyclopropenes has been developed. The reaction represents the first example of using cyclopropenes as a three-carbon unit in rhodium(III)-catalyzed C(sp(2))-H activations.

Palladium-Catalyzed Diarylmethyl C(sp3)–C(sp2) Bond Formation: A New Coupling Approach toward Triarylmethanes

Palladium-catalyzed reductive coupling reactions between N-tosylhydrazones and aryl halides lead to the formation of C(sp(3))-C(sp(2)) bonds. This approach provides a general route for the synthesis of triarylmethanes.

Cu(I)-catalyzed cross-coupling of conjugated ene-yne-ketones and terminal alkynes: synthesis of furan-substituted allenes.

A new method for the synthesis of furan-substituted allenes via Cu(I)-catalyzed coupling of conjugated ene-yne-ketones with terminal alkynes has been developed. A wide range of functional groups are tolerated, and the products are obtained in good to excellent yields under mild conditions. A copper carbene migratory insertion is proposed as the key step in this transformation with conjugated ene-yne-ketones as carbene precursors.

Directing group-assisted transition-metal-catalyzed vinylic C-H bond functionalization

Transition-metal-catalyzed C-H bond activation represents one of the most attractive research areas in organic synthesis. In contrast to the great developments made in directed C-H bond functionalization of arenes, the directing group-assisted activation of non-aromatic vinylic C-H bonds still remains challenging. During the recent years, significant progress has been made in this fascinating field with various functionalized alkenes, heterocycles and carbocycles being obtained. This article will focus on the recent achievements in the field of directing-group-assisted vinylic C-H bond functionalization.

Cu(I)-Catalyzed Synthesis of Furan-Substituted Allenes by Use of Conjugated Ene-yne Ketones as Carbene Precursors

The synthesis of furan-substituted allenes using conjugated ene-yne ketones as carbene source has been developed. For this reaction, bases play vital roles in controlling the reaction pathways, allowing for access to two types of allene products through trapping of different electrophiles. Mechanistically, the catalytic procedure generated a Cu(I) (2-furyl)carbene intermediate, which is subsequently followed by a migratory insertion process to afford nucleophilic organocopper species. The organocopper species thus generated can be trapped by proton or allyl halide, affording tri- or tetrasubstituted allenes, respectively. The reaction, which is characterized by its mild reaction conditions and the utilization of cheap copper(I) iodide as catalyst, allows for synthesis of a variety of furan-substituted allenes with a wide range of functional groups tolerance.

Catalyst-free cross-coupling of N -tosylhydrazones with chromium(0) Fischer carbene complexes: a new approach to diarylethanone

Cross-coupling of N-tosylhydrazones with chromium Fischer carbene complexes under catalyst-free conditions has been developed. This protocol employs stable carbene complexes and reactive diazo compounds, which are in situ generated from N-tosylhydrazones. Through hydrolysis of the initially formed methyl enolate products, the diarylethanone derivatives could be obtained in moderate to good yields.

Comparison of H2-Receptor Antagonist-and Proton-Pump Inhibitor-Based Triple Regimens for the Eradication of Helicobacter Pylori in Chinese Patients with Gastritis or Peptic Ulcer

This study compared the efficacy of an H2-receptor antagonist (H2RA)- and a proton-pump inhibitor (PPI)-based triple regimen for the eradication of Helicobacter pylori infection. Chinese patients with H. pylori-associated gastritis or peptic ulcer were randomized to receive the H2RA-based triple regimen (20 mg famotidine, 1.0 g amoxicillin and 0.4 g metronidazole) or the PPI-based triple regimen (20 mg omeprazole, 1.0 g amoxicillin and 0.4 g metronidazole) both twice daily for 1 or 2 weeks. Successful eradication of H. pylori was determined by the 13C-urea breath test and gastric mucosa histology at least 4 weeks after completion of antibiotic therapy. Eradication rates were 56.0% and 76.9% for the 1-week H2RA- and PPI-based triple regimens, respectively, and 81.6% and 82.1% for the 2-week regimens, respectively. The H. pylori eradication rate for the 2-week H2RA regimen was significantly higher than that for the 1-week regimen, but there were no significant differences between the 1- and 2-week PPI regimens. The two regimens proved equally effective in eradicating H. pylori infection.

Transition-metal-free synthesis of indole-fused dibenzo[b,f][1,4]oxazepines via Smiles rearrangement

A one-pot transition-metal-free approach for the synthesis of indole-fused dibenzo[b,f][1,4]oxazepines from 2-(1H-indol-2-yl)phenol and 1,2-dihalobenzenes or 2 halonitroarenes has been developed. The proposed mechanism for this transformation features a Smiles rearrangement favoured over a direct intramolecular nucleophilic cyclization, which affords the corresponding products in different regioselectivities. This reaction also features simple reaction conditions and wide functional group tolerance.