Programmable synthesis of difluorinated hydrocarbons from alkenes through a photocatalytic linchpin strategy.

The introduction of difluoromethylene moieties into organic molecules has garnered significant attention due to their profound influence on the physicochemical and biological properties of compounds. Nonetheless, the existing approaches for accessing difluoroalkanes from readily available feedstock chemicals remain limited. In this study, we present an efficient and modular protocol for the synthesis of difluorinated compounds from alkenes, employing the readily accessible reagent, ClCF2SO2Na, as a versatile "difluoromethylene" linchpin. By means of an organophotoredox-catalysed hydrochlorodifluoromethylation of alkenes, followed by a ligated boryl radical-facilitated halogen atom transfer (XAT) process, we have successfully obtained various difluorinated compounds, including gem-difluoroalkanes, gem-difluoroalkenes, difluoromethyl alkanes, and difluoromethyl alkenes, with satisfactory yields. The practical utility of this linchpin strategy has been demonstrated through the successful preparation of CF2-linked derivatives of complex drugs and natural products. This method opens up new avenues for the synthesis of structurally diverse difluorinated hydrocarbons and highlights the utility of ligated boryl radicals in organofluorine chemistry.

[Value of complement component 3 in predicting the prognosis of children with sepsis]. / 补体C3å¯¹å„¿ç«¥è„“æ¯’ç—‡æ‚£è€ é¢„åŽçš„é¢„æµ‹ä»·å€¼.

OBJECTIVES: To investigate changes in complement component 3 (C3) levels in children with sepsis and its correlation with the severity of sepsis and to explore the significance of C3 in predicting mortality in children with sepsis. METHODS: A retrospective analysis was conducted on 529 children with sepsis who were admitted to the Pediatric Intensive Care Unit in Hunan Children's Hospital between November 2019 and September 2021. The children were categorized into two groups based on their prognosis at day 28 after sepsis diagnosis: the survival group (n=471) and the death group (n=58). Additionally, the children were divided into normal C3 group (n=273) and reduced C3 group (n=256) based on the median C3 level (0.77 g/L) within 24 hours of admission. Clinical data and laboratory markers were compared between the groups, and assess the predictive value of C3 levels in relation to sepsis-related mortality. RESULTS: The death group exhibited significantly lower C3 levels compared to the survival group (P<0.05). Multivariate logistic regression analysis revealed that higher pediatric Sequential Organ Failure Assessment (p-SOFA) scores and lower C3 levels were closely associated with sepsis-related mortality (P<0.05). The receiver operating characteristic curve (ROC) analysis demonstrated that combination of p-SOFA scores and C3 levels yielded an area under the ROC curve of 0.852, which was higher than that of each indicator alone (P<0.05). CONCLUSIONS: C3 can serve as an indicator to assess the severity and prognosis of sepsis in children. The combination of p-SOFA scores and C3 levels holds good predictive value for mortality in children with sepsis.

Photoinduced Defluorinative Branch-Selective Olefination of Multifluoro (Hetero)arenes.

We report a photoredox platform for constructing styrenyl polyfluoro (hetero)arenes with branch selectivity by taking advantage of sulfinate as both a radical-relay precursor and a sacrificial nucleofuge. This protocol merges photoredox catalysis with radical-radical coupling and an elimination process in a one-pot operation and features good functional group tolerance, mild conditions, and a facile method to access polyfluoro (hetero)aryl derivatives of natural products and drugs.

Difluoromethylation of Unactivated Alkenes Using Freon-22 through Tertiary Amine-Borane-Triggered Halogen Atom Transfer.

The application of abundant and inexpensive fluorine feedstock sources to synthesize fluorinated compounds is an appealing yet underexplored strategy. Here, we report a photocatalytic radical hydrodifluoromethylation of unactivated alkenes with an inexpensive industrial chemical, chlorodifluoromethane (ClCF2H, Freon-22). This protocol is realized by merging tertiary amine-ligated boryl radical-induced halogen atom transfer (XAT) with organophotoredox catalysis under blue light irradiation. A broad scope of readily accessible alkenes featuring a variety of functional groups and drug and natural product moieties could be selectively difluoromethylated with good efficiency in a metal-free manner. Combined experimental and computational studies suggest that the key XAT process of ClCF2H is both thermodynamically and kinetically favored over the hydrogen atom transfer pathway owing to the formation of a strong boron-chlorine (B-Cl) bond and the low-lying antibonding orbital of the carbon-chlorine (C-Cl) bond.

[Using direct enzyme linked immunosorbent assay for the detection of IgG antibody on Bartonella henselae among healthy people in Changping, Beijing].

OBJECTIVE: To detect Bartonella henselae IgG antibody among healthy people in Changping, Beijing. METHODS: Using indirect enzyme linked immunosorbent assay (ELISA) and immunofluorescence antibody assay (IFA) to detect IgG antibody of Bartonella henselae among human beings. RESULTS: The sensitivity and specificity of ELISA were 70.6% and 91.6% respectively, with the positive predictive value of serological test as 82.2%, and the negative predictive value as 84.9%, based on results of IFA. The positive rate was 34.5% among 357 healthy people on indirect ELISA but was 35.6% among 239 people with IFA. CONCLUSION: The results indicated that the indirect ELISA was a very quick, sensitive and available method for detecting Bartonella henselae in human beings, as well as a high positive percent age of Bartonella henselae among the healthy people of Changping Beijing.

A highly regioselective amination of 6-aryl-2,4-dichloropyrimidine.

[reaction: see text]. A highly regioselective amination of 6-aryl-2,4-dichloropyrimidine with aliphatic secondary amines and aromatic amines has been developed which strongly favors the formation of the C4-substituted product. The reactions with aliphatic amines are carried out using LiHMDS as the base and are catalyzed by Pd, while the aromatic amines require no catalyst.

[3 + 2] Annulation of allylic silanes in acyclic stereocontrol: total synthesis of (9S)-dihydroerythronolide A.

The [3 + 2] annulation reactions of allylic silanes can be utilized to achieve acyclic stereocontrol. This method was employed as a key step in an enantioselective total synthesis of (9S)-dihydroerythronolide A. The key annulation reaction served to establish most of the stereochemistry of the target, including the two tetrasubstituted carbon stereocenters. The symmetry of the target molecule allowed it to be disconnected into two equally sized fragments, both of which were generated from the same annulation reaction. The two fragments were coupled using a tin(II)-mediated chelation-controlled aldol reaction of an alpha-benzyloxy ethyl ketone. This convergent total synthesis of (9S)-dihydroerythronolide A was accomplished with the longest linear sequence of 29 steps and in 5.4% overall yield.

Synthesis of (+/-)-5-epi-citreoviral and (+/-)-citreoviral and the kinetic resolution of an allylic silane by a [3 + 2] annulation.

[reaction: see text] The [3 + 2] annulation reaction of allylsilane 1 with an alpha-keto ester provided the highly substituted tetrahydrofuran 2 as a single diastereomer in high yield. The synthesis of (+/-)-5-epi-citreoviral and (+/-)-citreoviral has been accomplished with this annulation reaction as the key step. Using the pantolactone-derived alpha-keto ester, the allylsilane 1 has been resolved with high enantiomeric purity.