Intraspecific Differentiation of Styrax japonicus (Styracaceae) as Revealed by Comparative Chloroplast and Evolutionary Analyses.

Styrax japonicus is a medicinal and ornamental shrub belonging to the Styracaceae family. To explore the diversity and characteristics of the chloroplast genome of S. japonicus, we conducted sequencing and comparison of the chloroplast genomes of four naturally distributed S. japonicus. The results demonstrated that the four chloroplast genomes (157,914-157,962 bp) exhibited a typical quadripartite structure consisting of a large single copy (LSC) region, a small single copy (SSC) region, and a pair of reverse repeats (IRa and IRb), and the structure was highly conserved. DNA polymorphism analysis revealed that three coding genes (infA, psbK, and rpl33) and five intergene regions (petA-psbJ, trnC-petN, trnD-trnY, trnE-trnT, and trnY-trnE) were identified as mutation hotspots. These genetic fragments have the potential to be utilized as DNA barcodes for future identification purposes. When comparing the boundary genes, a small contraction was observed in the IR region of four S. japonicus. Selection pressure analysis indicated positive selection for ycf1 and ndhD. These findings collectively suggest the adaptive evolution of S. japonicus. The phylogenetic structure revealed conflicting relationships among several S. japonicus, indicating divergent evolutionary paths within this species. Our study concludes by uncovering the genetic traits of the chloroplast genome in the differentiation of S. japonicus variety, offering fresh perspectives on the evolutionary lineage of this species.

Photo-induced C(sp2)-H difluoroalkylation of anilines.

A photoinduced protocol for the direct difluoroalkylation of C(sp2)-H bonds in anilines under catalyst-free reaction conditions is presented. This transformation is characterized by a wide substrate scope, mild reaction conditions, and operational simplicity, and could serve as an alternative tool to established methods for the synthesis of difluoroalkylated anilines. Mechanistic studies suggest the formation of an electron-donor-acceptor (EDA) complex between anilines and difluoroalkyl bromides in this reaction.

Photoinduced Borylation of the Inert C(sp3)-O Bond of Alkyl Heteroaryl Ethers.

A photoinduced reductive Calkyl-O borylation of alkyl heteroaryl ethers with very negative reduction potential in the presence of 4-dimethylaminopyridine (DMAP) and bis(catecholato)diborane(B2cat2) was developed. Despite the high reducing power, various substrates with liable functional groups were well-tolerated as well as ethers derived from natural products and medicinal-relevant compounds. Mechanistic investigation implied that an intra-single electron transfer process in an electron donor-acceptor complex formed from ethers with the adduct of B2cat2 and DMAP should be involved.

In situ generation of electrophilic trifluoromethylthio reagents for enantioselective trifluoromethylthiolation of oxindoles.

An organocatalytic asymmetric trifluoromethylthiolation reaction via in situ generation of active electrophilic trifluoromethylthio species involving trichloroisocyanuric acid and AgSCF3 as a practical and easily handled electrophilic SCF3 source for CSP(3)-SCF3 bond formation was developed. Reactions with this one-pot version strategy occurred in good yields and excellent stereoselectivities to access enantiopure oxindoles bearing a SCF3-substituted quaternary chiral center. The straightforward process described here makes use of simple starting materials and proceeds under mild conditions, which will be useful in medicinal chemistry and diversity-oriented syntheses.

[Modification of the method for preparing rabbit liver VX2 tumor model and its MRI findings].

OBJECTIVE: To improve the method for preparing rabbit VX2 liver tumor model and observe the magnetic resonance imaging (MRI) features of the implanted tumors. METHODS: Sixteen adult New Zealand white rabbits were assigned randomly into 4 equal groups, and VX2 tumor tissues were implanted into the right and left liver lobes with spiral CT guidance. Plain and contrast-enhanced MR scan and pathological analysis were performed in different stages (14, 18, 22 and 26 days) after tumor implantation. RESULTS: Tumor implantation was successful in all the rabbits, and 18 to 22 days after tumor implantation, the diameters of the tumor ranged from 1 to 2 cm, which allowed observation and study. In plain MR scans, lower or equivalent tumor signal in comparison with hepatic parenchyma was observed, and contrast-enhanced scans produced obvious enhancement of the tumor edges. At 22 days after tumor implantation, obvious necrosis was observed in the center of the tumor. CONCLUSION: This method of preparing rabbit VX2 liver tumor model with spiral CT guidance is simple and convenient, and the tumors can be observed effectively with dynamic plain and contrast-enhanced MR scans.