3-Fluoroalkyl (CF3, CHF2, CH2F) Cyclobutane-Derived Building Blocks for Medicinal Chemistry: Synthesis and Physicochemical Properties

Synthesis and physicochemical characterization of all possible cis- and trans-1,3-disubstituted cyclobutane-derived amines and carboxylic acids bearing mono-, di- and trifluoromethyl groups at the C-3 position is disclosed. Tetramethylammonium fluoride (TMAF)- or morpholinosulfur trifluoride (Morph-DAST)-mediated nucleophilic fluorination of appropriate cis- and trans-diastereomeric substrates was used as the key step for the preparation of CH₂F- and CHF₂-substituted derivatives. To obtain the corresponding cis- and trans-isomeric CF₃-substituted derivatives, resolution of known 3-(trifluoromethyl)cyclobutanecarboxylic acid (obtained as a mixture of diastereomers) was applied. The proposed procedures were suitable for the preparation of corresponding fluoroalkyl-substituted cyclobutane-derived amines and carboxylic acids on up to 50 g scale. All 12 building blocks obtained were characterized by measuring dissociation constants (pK_a) and lipophilicities (LogP, for model derivatives) to evaluate the effect of the fluoroalkyl substituents on their physicochemical properties relevant to further drug discovery applications.     

Monitoring the Light-induced Isomerisation of the Prototypical Polycyclic Aromatic Hydrocarbons C10H8+ through Ion-Molecule Reactions

Structural rearrangements in ions are essential for understanding the composition and evolution of energetic and chemically active environments. This study explores the interconversion routes for simple polycyclic aromatic hydrocarbons, namely naphthalene and azulene radical cations (C₁₀H₈⁺), by combining mass spectrometry and vacuum ultraviolet tunable synchrotron radiation through the chemical monitoring technique. Products of ion-molecule reactions are used to probe C₁₀H₈⁺ structures that are formed as a function of their internal energies. Isomerisation from azulene radical cation towards naphthalene radical cation in a timescale faster than 80 μs was monitored, whereas no reverse isomerisation was observed in the same time window. When energising C₁₀H₈⁺ with more than 6 eV, the reactivity of C₁₀H₈⁺ unveils the formation of a new isomeric group with a contrasted reactivity compared with naphthalene and azulene cations. We tentatively assigned these structures to phenylvinylacetylene cations.     

Computational Studies on the Structures of Nanographenes with Various Edge Functionalities

Computational studies have often been carried out on hydrogen-terminated nanographenes (NGs). These structures are, however, far from those deduced from experimental observations, which have suggested armchair edges with two carboxy groups on the edges as dominant. We conducted computational studies on NGs consisting of C₄₂, C₆₀, C₇₈, C₉₆, C₁₄₂, and C₁₇₄ carbon atoms with hydrogen, carboxy, and N-methyl imide-terminated armchair edges. DFT calculations inform distorted basal planes and similar HOMO-LUMO gaps, indicating that the edge oxidation and functionalization do not very influence the electronic structure. Comparison of observed UV-vis spectra of carboxy- and N-octadecyl chain terminated NGs with calculated spectra of model NGs informs the contribution of π-π* transitions on the basal plane to the absorptions in the visible region. A dimeric structure of NG and octadecyl-installed NG demonstrate that both the distorted basal planes and the steric contacts among the functional groups widen the surface-to-surface distance thereby allowing the invasion of solvent molecules between the surfaces. This picture is consistent with the improved solubility of edge-modified NGs.     

Enantioselective Synthesis of [b]-Annulated Azepane Scaffolds

Cyclopenta-, benzo-, and cyclohepta[b]-annulated azepane scaffolds were prepared in two steps from optically active cyclic α-allyl-β-oxoesters. The first step was ruthenium-catalyzed olefin cross metathesis with acrylonitrile. The second step was palladium-catalyzed dihydrogenation which consists of three consecutive processes: The hydrogenation of the C−C double and C−N triple bonds was followed by the reductive amination via the iminium ion formed in situ from the primary amino function and the endocyclic carbonyl group. This last step gave, stereoselectively, the annulated azepanes with relative trans-configuration. The amino function and the ester group define two points for further diversification of the scaffolds. The trifluoroacetyl derivatives allowed to establish the enantiopurity of the products to be 97–98 % ee by GLC on a chiral phase. The relative trans-configurations and in one case also the absolute (R,R)-configuration was established by X-ray crystallography.     

Triethylamine-Mediated Transformation of Phosphonates into Phosphonamidates

Organophosphorus compounds such as phosphonamidates are gaining attention across different fields of chemistry, with interesting applications as pharmaceuticals, or pesticides. However, practical application of phosphonamidates is complicated by their difficult syntheses which often involve expensive or unstraightforward reagents and harsh conditions. To remedy these issues, we present a flexible, room temperature synthesis for novel P-alkylphosphonamidates without the need for intermediary purification. Commonly available phosphonates are first chlorinated by use of oxalyl chloride and phosphonylaminium salts are used to mediate the harsh reactivity of phosphonochloridates, giving rise to the desired products. We demonstrate the compatibility of our protocol with primary and secondary amines, as well as with different phosphonate esters. The proposed pathway also enables the synthesis of primary phosphonamidates using ammonium acetate as a cheap and safe alternative for ammonia. In future research, this protocol will also enable the synthesis of bioactive targets that are incompatible with current protocols.     

Palladium-Catalyzed Hydroaminocarbonylation of Olefins with Aliphatic Amines without Additives

Palladium-catalyzed hydroaminocarbonylation reactions of olefins using aliphatic amines were performed under carbon monoxide atmosphere. Despite the strong basicity of the applied nucleophiles, the targeted amides were successfully synthesized in the absence of acidic additives. Styrene, oct-1-ene and isoprene were transformed to the corresponding amide isomers in moderate to good isolated yields under optimized reaction conditions. Various aliphatic amines were used as N-nucleophiles. The effect of chiral diphosphines on product distribution, that is, on chemo-, regio- and enantioselectivities was also studied. Plausible explanation was given for the additive-free hydroaminocarbonylation reaction.     

酸溶-电感耦合等离子体发射光谱法测定白云石和菱镁石中主次元素

利用电感耦合等离子体原子发射光谱仪( ICP-AES)建立白云石和菱镁石中铝、钙、铁、镁、锰、磷、硅、锶的测定方法。研究了酸体系、温度及消解方式对试样消解的影响,结果表明,使用5 mL盐酸和硝酸混合酸(1：3)-0.75 mL氢氟酸-5 mL水以密闭消解的方式在150 ℃下消解白云石和菱镁石30min,并以2mL饱和硼酸络合多余的氢氟酸,可以得到澄清消解液。通过白云石和菱镁石中铝、钙、铁、镁、锰、磷、硅、锶的谱线干扰情况,选择Al 308.215 nm、Ca 318.127 nm、Fe 261.187 nm、Mg 277.983 nm、Mn 257.61 nm、P 213.618 nm、Si 251.611 nm、Sr 421.552 nm作为分析线,各元素的校准曲线在线性范围内线性关系良好,相关系数均不小于0.999。按照实验方法测定白云石和菱镁石标准物质,各元素结果的相对标准偏差 (RSD, n=6)为0.89~3.19%,测定值与认定值无显著性差异。本方法有效解决了白云石和菱镁石快速有效溶解及准确测定问题。     

Asymmetric Synthesis of a Quaternary Carbon Stereogenic Center by Organocatalysis Using a Primary Amino Acid and Its Salt

In this personal account, our recent developments on the asymmetric synthesis of a quaternary carbon stereogenic center by organocatalysis using a primary amino acid and its salt as a catalyst are described in three chapters: (1) conjugate addition to nitroalkenes and vinyl ketones, (2) nucleophilic addition to π-allyl palladium complexes, and (3) nucleophilic substitution reactions with allyl and propargyl halides. By these methods, asymmetric α-allylation of α-branched aldehydes and ketones smoothly proceeded to give γ-nitroaldehydes, ketoaldehydes, α-allylated aldehydes, and α-allylated β-ketoesters possessing a quaternary carbon stereogenic center in good yields with high enantioselectivities.     

脂肪胺类化合物氨基15N NMR化学位移规律的研究

提出了计算脂肪胺类化合物的¹⁵N NMR化学位移的经验公式：δ_cal（¹⁵N）=-380.2+ΣΔα+ΣΔβ+ΣΔγ+ΣΔδ+ΣC,结合最小二乘法通过线性回归得到了11种取代基参数,计算结果以133种化合物的133个¹⁵N NMR化学位移数据为样本点进行回归检验,置信度为99.5 %,约有94.7 %的¹⁵N NMR化学位移计算值的计算误差小于5.0（相对误差小于0.5 %）.     

原子吸收光谱法测定烟叶中的重金属总量及形态分析

采用火焰原子吸收光谱法测定烟叶中Mn,Cu,Zn元素,石墨炉原子吸收光谱法测定Cd,Cr,Pb元素,以HNO3-H2O2微波消解法获取烟叶中的重金属总量,以超声水提取法获取水溶态重金属进行初级形态分析,以Tessier逐级提取法获取5种形态的重金属进行次级形态分析。实验结果表明,原子吸收光谱法检测6种重金属线性良好,相关系数(r2)不低于0.998 8,检出限为0.16~3.1μg·L-1。烟叶样品中Mn,Cu,Zn,Cd元素主要以可交换态和碳酸盐结合态的形式存在;Cr主要以残渣态的形式存在;而Pb主要以碳酸盐结合态和残渣态的形式存在。