A Minor New Flavone from Scutellaria baicalensis Georgi

A new flavone,6,2′-dihydroxy-5,7,8,6′-tetramethoxyflavone,was isolated from the roots of Scutellaria baicalensis. Its structure was established on the basis of spectral evidences.     

Enantioselective Total Synthesis of Four Styrylpyrone Derivatives

The first enantioselective total synthesis of 5-acetoxygoniothalamin 1 and 5-acetoxyisogoniothalamin oxide 2 was achieved through the Sharpless kinetic resolution of recemic secondary 2-furylmethanol 5 and the Mitsunobu reaction. At the same time we developed a short synthetic route for 6R-( )-goniothalamin 3 and (6R,7R,8R)-( )-goniothalamin oxide 4. And according to this route the configuration of 5-acetoxygoniothalamin 1 was confirmed as (5S,6S).     

Direct synthesis of Poly(Ԑ-Caprolactone)-block-poly (glycidyl methacrylate) copolymer and its usage as a potential nano micelles carrier for hydrophobic drugs

Ring-opening (ROP) and enzymatic copolymerization (ECP) are among the most widely used approaches for synthesizing copolymers of polycaprolactone (PCL). It involves multiple-step reactions and the utilization of enzymes that make the process a lot more complicated, time consuming, and expensive. Atom transfer radical polymerization (ATRP) has been adopted to synthesize a novel amphiphilic copolymer in our study. The study presents a method to eliminate the ROP/ECP multiple steps in monomer polymerization thus making the process simpler and smoother. The synthesis of cationic polymer micelles copolymer of PCL-PGMA (polycaprolactone grafted poly glycidyl methacrylate) was carried out using direct functionalization of hydroxy group in crude PCL to achieve a higher degree of functionalization, i.e., 12.8% for macroinitiator. FTIR and ¹H-NMR confirmed the successful synthesis of the copolymer with better control over the molecular weight with a PDI (1.84). DSC and XRD results showed the reduction of crystallinity by 86.81%, making copolymer more compatible for drug delivery application. The synthesized copolymer was further converted to nano-micelles drug carrier having an average size of 96.08 ± 21.22 nm. The drug encapsulation efficiency achieved was 60.0 ± 1.7%, and nano-micelles rendered a slow and controlled release of naproxen with long-term storage stability.     

Iron‐Catalyzed C(sp2)H and C(sp3)H Methylations of Amides and Anilides

The so‐called magic methyl effect significantly boosts the bioactivities and physical properties of pharmacologically active drugs. Direct introduction of the methyl group by C?H activation was accomplished with a versatile iron catalyst, which enabled the C?H methylation of (hetero)benzamides, anilides, alkenes, and even alkanes by triazole assistance in a chemo‐, site‐ and diastereo‐selective fashion.     

Activation of Strong Boron–Fluorine and Silicon–Fluorine σ‐Bonds: Theoretical Understanding and Prediction

The oxidative addition of BF₃ to a platinum(0) bis(phosphine) complex [Pt(PMe₃)₂] ( 1 ) was investigated by density functional calculations. Both the cis and trans pathways for the oxidative addition of BF₃ to 1 are endergonic (ΔG°=26.8 and 35.7 kcal mol^?1, respectively) and require large Gibbs activation energies (ΔG°^≠=56.3 and 38.9 kcal mol^?1, respectively). A second borane plays crucial roles in accelerating the activation; the trans oxidative addition of BF₃ to 1 in the presence of a second BF₃ molecule occurs with ΔG°^≠ and ΔG° values of 10.1 and ?4.7 kcal mol^?1, respectively. ΔG°^≠ becomes very small and ΔG° becomes negative. A charge transfer (CT), F→BF₃, occurs from the dissociating fluoride to the second non‐coordinated BF₃. This CT interaction stabilizes both the transition state and the product. The B?F σ‐bond cleavage of BF₂Ar^F (Ar^F=3,5‐bis(trifluoromethyl)phenyl) and the B?Cl σ‐bond cleavage of BCl₃ by 1 are accelerated by the participation of the second borane. The calculations predict that trans oxidative addition of SiF₄ to 1 easily occurs in the presence of a second SiF₄ molecule via the formation of a hypervalent Si species.     

Catalytic Asymmetric Reactions of 4‐Substituted Indoles with Nitroethene: A Direct Entry to Ergot Alkaloid Structures

A domino Friedel–Crafts/nitro‐Michael reaction between 4‐substituted indoles and nitroethene is presented. The reaction is catalyzed by BINOL‐derived phosphoric acid catalysts, and delivers the corresponding 3,4‐ring‐fused indoles with very good results in terms of yields and diastereo‐ and enantioselectivities. The tricyclic benzo[cd]indole products bear a nitro group at the right position to serve as precursors of ergot alkaloids, as demonstrated by the formal synthesis of 6,7‐secoagroclavine from one of the adducts. DFT calculations suggest that the outcome of the reaction stems from the preferential evolution of a key nitronic acid intermediate through a nucleophilic addition pathway, rather than to the expected “quenching” through protonation.     

Brønsted Acidity and Aluminum Substitution Characteristics of Si(nAi) Sites in Zeolites: A Theoretical MNDO Calculation

The Brønsted acidity of the various Si(nAl) sites present in zeolites is evaluated from proton binding energy and LUMO energy calculated by the semiempirical MNDO quantum chemical method. The two calculated energy values both exhibit a linear correlation with the existing ²⁹Si NMR chemical shift and the IR hydroxyl stretching frequency data. The inter-convertibility between different Si(nAl) sites during an alumination or dealumination process is also evaluated based on the calculated substitution energy. The results indicate that alumination processes are less favorable to occur in zeolites than dealumination processes and the latter is more likely to occur for Si(nAl) clusters that contain the maximum number of aluminum nearest neighbors.     

The Crystal Structure of Pb8FeIIFeF24: an ordered Fluorite-like Compound

Pb₈Fe^IIFeF₂₄ is triclinic: a = 20.118(3) Å, b = 5.597(1) Å, c = 9.440(2) Å, α = 89.75(2)°, β = 105.79(2)°, α = 89.38(2)°, Z = 2. The structure is solved in the unconventional space group C1 , from X-ray single crystal data using 1 641 independent reflections (R = 0.048, R_w = 0.051). It is built up from the stacking of two subnetworks along the a axis: fluorite-like [Pb₈F₁₀]_n⁶ⁿ⁺ layers and infinite dimetallic [Fe^IIFeF₁₄]_n^6n? double-chains of corner-sharing octahedra running along the b axis.     

希土水杨酸与8─羟基喹啉三元配合物研究

合成了六种希土（ＲＥ）－水杨酸（Ｈ２ｓａｌ）－８－羟基喹啉（Ｈｈｑ）三元固体配合物，其通式为ＲＥ（Ｈｓａｌ）２·ｈｑ（ＲＥ＝Ｙ，Ｌａ，Ｎｄ，Ｓｍ，Ｈｏ，Ｅｒ）．通过元素分析、摩尔电导、ＩＲ、Ｆａｒ－ＩＲ、ＵＶ－Ｖｉｓ、ＴＧ－ＤＴＡ分析，研究了配合物的组成、性质和成键特性．通过抑菌试验表明配合物对于霉菌具有抑真菌能力．