Methyl 3,3,3-trifluoropyruvate: an improved procedure starting from hexafluoropropene-1,2-oxide; identification of byproducts

Optimized laboratory-scale preparation of methyl 3,3,3-trifluoropyruvate (3, MTFP) has been developed starting from industrial hexafluoropropene-1,2-oxide (1, HFPO) via methyl 2,3,3,3-tetrafluoro-2-methoxypropanoate (2, MTPr), which was transformed to 3 using sulfuric acid with isolated yields up to 81%. Byproducts formed in the transformation of 2 to 3, viz. methyl trifluoroacetate (4, MTAc), methyl 3,3,3-trifluoropyruvate hydrate (5), methyl hemiacetal of trifluoropyruvate (6), a dimer of methyl 3,3,3-trifluoropyruvate hydrate (7, DimMTP), and methyl fluorosulfate (8, Sulf) were identified and their amounts determined under various experimental conditions. Potential reaction pathways leading to the formation of the byproducts are discussed.     

Reductive deacetylation of 3,3,3-trifluoro-1-(2-thenoyl)acetone

The reaction of 3,3,3-trifluoro-1-(2-thenoyl)acetone with sulfur—hydrazine hydrate—alkali and hydrazine hydrate—alkali systems is effected by reductive fission of the trifluoroacetyl group and leads to the formation of nitrogen-containing derivatives of 2-acetylthiophene. Sodium polysulfide assists the reductive fission of 3,3,3-trifluoro-1-(2-thenoyl)acetone. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1006–1010, July, 2006.     

Fluorinated butanolides and butenolides : Part 9. Synthesis of 2-(trifluoromethyl)butan-4-olides by Wittig reaction using methyl 3,3,3-trifluoropyruvate

2-(Trifluoromethyl)butan-4-olides 13 and 14 were prepared by a three-step synthesis starting from a Wittig reagent and methyl 3,3,3-trifluoropyruvate (1) as a building block. The Wittig reaction of (2-oxoalkyl)triphenylphosphonium bromides with pyruvate 1 gave intermediate 4-oxobutenoates 8 and 9, which were stepwise selectively reduced with zinc borohydride firstly at the double bond and subsequently at the oxo group to afford unstable 4-hydroxy-2-trifluoromethylalkanoates 11 and 12, which cyclised spontaneously to the end butenolides 13 and 14.     

2-bromo-3,3,3-trifluoropropene: A facile trifluoromethylacetylene anion synthon

The introduction of trifluoromethylacetylene units into organic compounds has been further studied and extended. The direct reaction of two equivalents of Lithium Diisopropylamide with 2-bromo-3,3.3-trifluoropropene gave lithium trifluoromethylacetylide, the anion of which was trapped in greater than 90% overall yield with a variety of electrophiles.     

HSCN condensation with ulosides: preferred formation of carbohydrate-fused hemiaminals of the 4-hydroxy-1,3-oxazolidine-2-thione type

Selected ulofuranosides and ulopyranosides react with thiocyanic acid to give good yields of stable carbohydrate-fused hemiaminal 1,3-oxazolidine-2-thiones.     

Methyl 2-methoxytetrafluoropropionate as a synthetic equivalent of methyl trifluoropyruvate in the Claisen condensation. The first synthesis of 2-(trifluoroacetyl)chromones and 5-aryl-2-hydroxy-2-(trifluoromethyl)furan-3(2H)-ones

2-(Trifluoroacetyl)chromones and 5-aryl-2-hydroxy-2-(trifluoromethyl)furan-3(2H)-ones were obtained in good yields via the Claisen condensation of acetophenones with methyl 2-methoxytetrafluoropropionate, followed by sulfuric acid-mediated deprotection of the reaction products.     

New terphenyl liquid crystals terminated by 2-chloro-3,3,3-trifluoropropenyl group

New liquid crystal (LC) compounds composed of terphenyl as a core and 2-chloro-3,3,3-trifluoropropenyl terminal group were synthesised. Their structures were confirmed by nuclear magnetic resonance, mass spectra and infrared spectrometry. The mesomorphic and physical properties were evaluated. The results show that these compounds have a smectic phase, large dielectric anisotropy, high birefringence and suitable rotational viscosity. The lateral fluorine substitutions lead to a large perpendicular component of the dielectric constant, and a small value of Δε/ε_⊥. These characteristics are significant for the fringe-field switching LC display mode.     

Convenient synthesis of trifluoromethylated 2-pyrrolidone and 2-pyrrolone derivatives

The reaction of a set of enamines with methyl trifluoropyruvate and its imine was investigated. As a result, a simple procedure for synthesis of trifluoromethylated 2-pyrrolidone and 2-pyrrolone derivatives has been developed.     

Novel rearrangement of 1H-2,3-benzoxazines to cyclic N-acyl hemiaminals: application to the synthesis of 1-arylnaphthalene skeletal congeners

The rearrangement of 1H-2,3-benzoxazine derivatives has been investigated. The reaction affords cyclic hemiaminal derivatives for their conversion to the corresponding 1-arylisobenzofurans, which can be trapped by various dienophiles to afford skeletal congeners of 1-arylnaphthalene lignans.     

Nucleophilic addition of 3,3,3-trifluoropropynyllithium to d-glyceraldimine: Concise synthesis of both enantiomers of 5,5,5-trifluoronorvaline

3,3,3-Trifluoropropynyllithium, in situ generated by treatment of 2-bromo-3,3,3-trifluoro-1-propene 1 with 2.0 equiv. of LDA at −78 °C, was trapped with d-glyceraldimine 2 to give trifluoromethylated propargylic amine 4 in 55% yield. Starting from the key intermediate 4, Boc-protected (R)-5,5,5-trifluoronorvaline and (S)-5,5,5-trifluoronorvaline were concisely synthesized over three steps in 62% and 63% yield, respectively.     

超分子结构甲基橙插层水滑石的组装及其光热稳定性研究

甲基橙是一种酸性染料,但因为它的光和热稳定性较差,使其应用范围和使用效果受到了一定限制.以Mg_0.67Al_0.33(OH)₂(CO₃)_0.165·0.58H₂OLDHs为前体,采用离子交换法,将甲基橙插入到LDHs层间,借助XRD,FTIR,UV-Vis和TG-DTA等手段对样品进行表征.结果表明,甲基橙阴离子可以完全取代前体层间的CO₃^2-离子,组装得到晶体结构良好的甲基橙插层LDHs.对其结构进行研究发现,LDHs主体层板与客体甲基橙阴离子之间存在静电吸引、氢键和其它弱化学键相互作用,具有超分子结构特征.该超分子结构材料不仅保持了甲基橙本身的颜色,而且与甲基橙相比,其耐光性和耐热性均有大幅度的提高.     

Methyl hydrogen peroxide dimer: A structural study

Methyl hydrogen peroxide (MHP) exhibits a tendency to form a stable dimer by hydrogen-bonding. Ab initio theoretical investigations on methyl hydrogen peroxide dimer (MHPD) carried out herein lead to several energetically stable structures that have a direct bearing on the reactivity of the monomer in terms of its molecular electrostatic potential (MESP). To gauge the role played by the electron-correlation in lending stability to MHP and its dimer, we employ the density functional theory (DFT) (as implemented by B3LYP-functional), and subsequently second order Møller-Plesset (MP2) perturbation theory, using the basis sets 6-31G(d, p) and 6-311++G(2d, 2p). Simulated infra-red vibrational spectra lead to spectral intensity redistribution upon dimerization. Energetically the lowest MHPD is endowed with inversion symmetry and has two hydrogen bonds, while three other structures emerge: one energetically very close with two H-bonds, and the two others, with three H-bonds each, yet higher by about 2 kcal mol⁻¹.     

TiO2光电化学电池催化氧化甲基红

以钛基TiO₂薄膜为光阳极，研究了光电化学电池中阳极光催化降解偶氮染料甲基红的动力学. 结果表明，短接光电化学电池分隔了光催化过程的阴、阳极反应，有利于抑制光生载流子的复合，提高光催化氧化速率. 相同实验条件下短路光电流越大，则甲基红降解速率越高. 在基底和TiO₂薄膜之间夹层SnO₂得到组装电极Ti/SnO₂/TiO₂，进一步提高了光生载流子的分离效率；同时采用电化学阻抗谱（EIS）评价了电极的光催化性能.     

Preparation, characterization and thiol-thione tautomeric studies of 2-thiono-4-methyl-5-(2,2,2-trifluoro-1-trifluoromethylethyl)-1,3-thiazoline

The synthesis of a new trifluoromethyl 2-mercapto-1,3-thiadiazole derivative from 5,5,5-trifluoro-4-(trifluoromethyl)-3-penten-2-one, its structural study in the solid state and in the liquid phase and the thiol-thione tautomeric equilibrium study of the title compound are reported. The crystalline structure shows short intermolecular FF contacts. Theoretical calculations using HF and DFT methods were performed. Vibrational spectra were calculated for both tautomers and compared with experimental data. The experimental and theoretical results can be interpreted in terms of the existence of a thione tautomer in the solid and in solution.     

Reaction ofN-(3,3,3-trifluoro-2-trifluoromethylprop-1-enyl)dimethylamine with MgSO4·7H2O. Synthesis of 4,4-difluoro-5-trifluoromethyl-2-(2,2,2-trifluoro-1-trifluoromethylethyl)-4H-1,3-dioxine andcis/trans-3-dimethylamino-2-trifluoromethacryloyl fluoride

4,4-Difluoro-5-trifluoromethyl-2-(2,2,2-trifluoro-1-trifluoromethylethyl)-4H-1,3-dioxine andcis/trans-3-dimethylamino-2-trifluoromethacryloyl fluoride were obtained by reaction ofN-(3,3,3-trifluoro-2-trifluoromethylprop-1-enyl)dimethylamine with MgSO₄·7H₂O. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1069–1071, May, 1997.     

酸催化三聚甲醛与甲酸甲酯偶联反应过程的分析

以硫酸为催化剂,研究了三聚甲醛与甲酸甲酯偶联合成乙醇酸甲酯和甲氧基乙酸甲酯的反应中,催化剂浓度、原料配比、反应温度、反应时间等条件对反应过程的影响,通过对产物收率和系统压力变化的分析,并结合与其它不同酸强度催化剂的对比,得到甲醛的活化是偶联反应的速率控制步骤,催化剂的酸强度决定其对甲醛的活化能力,是影响偶联反应的主要因素.     

新型N-[cis-3-(2-氯-3,3,3-三氟丙烯基)-2,2-二甲基环丙烷基羰基]-N'-芳氧乙酰肼的合成与生物活性

为了寻找高效、低毒的农药先导化合物,利用cis-3-(2-氯-3,3,3-三氟丙烯基)-2,2-二甲基环丙烷酰氯(1)与芳氧乙酰肼的缩合反应,合成了12种未见文献报道的目标化合物,其结构经IR,1H NMR,MS和元素分析测试技术确证.初步的生物活性测定结果表明,部分目标化合物在100 mg/L浓度下对双子叶植物(油菜)显示出良好的除草活性;同时,部分化合物在200 mg/L浓度下对蚕豆蚜虫(Aphis fabas)显示出较好的杀虫活性.     

Regio- and stereo-specific preparation of (E)-1-aryl-3,3,3-trifluoro-1-iodo-propenes and their palladium-catalyzed reaction with terminal alkynes

A new type of iodo-containing trifluoromethylated building blocks were synthesized. The reaction of 1-aryl-3,3,3-trifluoropropynes 1 with lithium iodide in acetic acid at 75 °C gave (E)-1-aryl-3,3,3-trifluoro-1-iodo-propenes 2 in high yield, which undergo the palladium-catalyzed Sonogashira reaction with terminal alkynes afforded trifluoromethyl-containing 1,3-enynes in high yield.     

Alternating Copolymers of Limonene with Methyl Methacrylate: Kinetics and Mechanism

The radical copolymerization of limonene (optically active) with methyl methacrylate in xylene at 80±0.1°C for 1 hr, initiated by benzoyl peroxide (BPO) yield alternating copolymer(s), under the inert atmosphere of nitrogen, as evidenced by reactivity ratios r₁ (MMA)=0.07 and r₂ (limonene)=0.012 using the Kelen–Tüdos method. The kinetic expression is Rα[I]^0.5[MMA]^1.0[Lim.]^?1.0. The decrease in the rate of polymerization with increase in concentration of limonene is due to penultimate unit effect. The overall energy of activation is calculated as 49 kJ/mole. FTIR of the copolymer(s) shows the characteristic frequencies at 1732.40 and 2951.40 cm^?1 due to –OCH₃ of MMA and aromatic C–H stretching of limonene, respectively. ¹H NMR spectra shows peak at 3.8–4.1 δ and 5.3–5.6 δ due to –OCH₃ of MMA and trisubstituted olefinic protons [–CH=CH–CH₂–] of limonene, respectively.