Palladium-Catalyzed Direct Arylation of Free NH2-Substituted Thiophene Derivatives

Phylogenetic characterization of genes encoding for viral envelope glycoprotein (ORF5) and nucleocapsid protein (ORF7) of porcine reproductive & respiratory syndrome virus found in Malaysia in 2013 and 2014

Background

Porcine reproductive and respiratory syndrome (PRRS) is one of the most expensive diseases of modern swine production & results in annual economic losses and cost the industry over 600 million USD in U.S. alone and billions of dollars worldwide. Two atypical PRRS cases were observed in 2013 and 2014 characterized by late-term abortion, fever and sudden increase in sow mortality which persisted for a prolonged period of time.

Methods

Lungs, lymph nodes and other samples were collected for disease investigation. Sequencing of the viral envelope glycoprotein (ORF5) and nucleocapsid protein (ORF7) of PRRSV was done using the BigDye Terminator v3.1 cycle sequencing kit chemistry. The phylogenetic tree was constructed by using the Maximum Likelihood method, generated by Mega 6.06®.

Results

Analysis of the ORF5 and ORF7 showed high degree of sequence homology to PRRSV parent vaccine strain VR-2332, RespPRRSV and other mutant/chimeric virus strains.

Conclusions

Our study suggests that recombination events between vaccine strains and field isolates may contribute to PRRSV virulence in the field.

Palladium-catalyzed direct C–H arylations of dioxythiophenes bearing reactive functional groups: a step-economical approach for functional π-conjugated oligoarenes

A phosphine-free C–H arylation of dioxythiophenes bearing unprotected functional groups affords oligoarenes with good yields.

Direct C-H arylation of thiophenes at low catalyst loading of a phosphine-free bis(alkoxo)palladium complex

An efficient phosphine-free direct C-H arylation of thiophenes at the α-position has been developed at low catalyst loading of bis(alkoxo)palladium complex (Cat.I, 0.1-0.2 mol %). The developed synthetic method can be applied to the synthesis of α-aryl/heteroaryl thiophenes from aryl or heteroaryl bromides in good to excellent yields and is compatible with the substrates bearing electron-donating or electron-withdrawing groups. The reactivities of the 2- and 5-positions of thiophenes are equivalent and not dependent on steric hindrance under optimal conditions. This condition can also be applied to other heterocyclic moieties such as benzothiophene, benzofuran, and pyrrole with high conversion yields.

Synthesis of 2,5-diaryl-substituted thiophenes as helical mimetics: towards the modulation of islet amyloid polypeptide (IAPP) amyloid fibril formation and cytotoxicity

A range of 2,5-diarylated thiophenes were synthesised as small molecule mimetics of the α-helix to modulate the amyloidogenesis and cytotoxic effect of islet amyloid polypeptide (IAPP). 3-Substituted thiophene-2-carboxylic acids were used as key intermediates and functionalised by palladium decarboxylative cross-coupling and direct C-H activation successively with overall yields ranging from 23 to 95 %. The effect of the ligands on IAPP amyloid fibril formation was evaluated with the thioflavin T (ThT) fluorescence-based assay. Furthermore, the capacity of these compounds to inhibit the cytotoxic effect of IAPP was assessed using β-pancreatic cells.

Synthesis of heteroarylated polyfluorobiphenyls via palladium-catalyzed sequential sp2 C-H bonds functionalizations

The higher reactivity of C5-H bonds of heteroarenes as compared to C-H bonds of bromopolyfluorobenzenes for palladium-catalyzed direct arylation allows the selective synthesis of the polyfluoroaryl-heteroarenes in moderate to high yields, without C-H bond functionalization of the polyfluorobenzene ring. In most cases, low loading of Pd(OAc)2 catalyst (0.5-1 mol %) was employed. Then, from these heteroarylated polyfluorobenzenes, the palladium-catalyzed C-H bond functionalization of the polyfluorobenzene ring allows the synthesis of heteroarylated polyfluorobiphenyls.