Recent progress toward the total synthesis of humulanolides

The humulanolides are a series of sesquiterpene lactones, most of which have unique and challenging structure. The humulanolides have exhibited anticancer activity. The combinations of fascinating structural motifs and promising pharmacological properties have prompted significant interest in the synthetic community. In this review, we provide a summary of recent progress regarding the total synthesis of humulanolides.     

Transition-metal-free trifluoromethylthiolation and difluoromethylthiolation of thiols with trifluoromethanesulfonyl chloride and difluoromethanesulfonyl chloride

Triphenylphosphine-mediated metal-free trifluoromethylthiolation and difluoromethylthiolation of thiols by CF₃SO₂Cl and CHF₂SO₂Cl to synthesize trifluoromethyl disulfides and difluoromethyl disulfides, respectively, was achieved at room temperature. Iodine generated in situ from iodide facilitated this reaction via the formation of iodotriphenylphosphonium iodide which could serve as a reducing agent in this transformation. Readily available reagents and mild reaction conditions without transition-metals allow this protocol to be more practical than traditional methods.     

One step synthesis of indirubins by reductive coupling of isatins with KBH4

One step synthesis of the natural product indirubin by reductive coupling of isatin with KBH₄ is described and a possible mechanism for the reaction is proposed. Eleven indirubin derivatives were obtained easily from the corresponding substituted isatin.     

The colorimetric and ratiometric fluorescent detection of cyanide and sulfide in live cells,application for logic gate and bioimging

We described the design and synthesis of a colorimetric and ratiometric fluorescent probe based on a conjugated π-electron system that displayed differential fluorescence responses towards cyanide and sulfide and demonstrated its utility in intracellular ion imaging and logic gate.     

Synthesis of polysubstituted 5-hydroxyhydantoins via ring-opening of isatins

A simple and efficient tandem reaction approach was developed for the synthesis of 5-hydroxyhydantoins from one-pot reaction of isatins, phthalic anhydride or succinic anhydride, and 1,3-dimethylurea (1,3-diethylurea). The products were gained through the ring-opening of isatins process. The advantages of this report are simple operation, mild reaction conditions, good yields and easily available raw materials. It was very important for us to obtain the intermediate product and that provided a solid basis for the correct interpretation of the reaction mechanism.     

Synthesis of 2,3,6-trisubstituted pyridines by transition-metal free cyclization of 1,3-diynes with amino acids

Amino acids are firstly employed in transition-metal free heterocyclization reaction of 1,3-diynes in the presence of K₃PO₄ and DMSO at 120 °C. This method produces 2,3,6-trisubstituted pyridines with up to 86% yield. The –CO₂H group on the amino acids is crucial for this heterocyclization reaction. The mechanism of such a heterocyclization reaction is discussed, as well.     

Lateral flow test for visual detection of silver(I) based on cytosine-Ag(I)-cytosine interaction in C-rich oligonucleotides

The authors describe an oligonucleotide-based lateral flow test for visual detection of Ag(I). The assay is based on cytosine-Ag(I)-cytosine [C-Ag(I)-C] coordination chemistry to capture gold nanoparticle (AuNP) tags in the test zone. A thiolated C-rich oligonucleotide probe was immobilized on the AuNPs via gold-thiol chemistry, and a biotinylated C-rich oligonucleotide probe was immobilized on the test zone. The AuNPs labelled with C-rich oligonucleotides are captured by Ag(I) ions in the test zone through the C-Ag(I)-C coordination. The resulting accumulation of AuNPs produces a readily visible red band in the test zone. Under optimized conditions, the test is capable of visually detecting 1.0 ppb of Ag(I) which is 50 times lower than the maximum allowable concentration as defined by the US Environmental Protection Agency for drinking water. Hence, the test is inexpensive and highly sensitive. It was applied to the detection of Ag(I) in spiked samples of tap water and river water. In our perception, the test is a particularly valuable tool in limited resource settings.

Open image in new window

Graphical abstract Graphical Abstract

     

Photometric determination of free cholesterol via cholesterol oxidase and carbon nanotube supported Prussian blue as a peroxidase mimic

Microchimica Acta - The authors describe a photometric method for the determination of free cholesterol based on the oxidation of cholesterol by the catalytic action of the enzyme...     

Synthesis and Thermal Performance of Polyurea Microcapsulated Phase Change Materials by Interfacial Polymerization

Microencapsulated phase change materials with paraffin as the core material were synthesized by interfacial polymerization of isophorone diisocyanate with diethylene triamine. The particle size and particle size distribution, morphology, thermal performance and the encapsulation efficiency of the prepared materials were investigated. The results of Fourier transform infrared spectrometer and X-ray photoelectron spectroscopy suggested that the paraffin core was well encapsulated by the polyurea resin. The particle size of the prepared materials decreased and its distribution became narrow with the increase of the emulsification time, stirring speed and emulsifier amount. The thermal gravimetric analysis indicated that the prepared materials exhibited good thermal stability, while the differential scanning calorimetry their high encapsulation efficiency.