Halogenation of fluorinated cyclic 1,3-dicarbonyl compounds: new aspects of synthetic application

In order to elaborate on an approach towards 2-(fluoroacyl)phenols being the superior alternative to the conventional Fries-rearrangement based methodology, the behaviour of cyclic fluorinated 1,3-dicarbonyls in reactions with halogenating agents was examined. The synthetic relevance of the polyhalogenated compounds obtained was demonstrated by the synthesis of several new heterocycles. An aromatization via a halogenation-dehydrohalogenation sequence proved to be a rewarding synthetic route to 2-(fluoroacyl)phenols and previously unknown 3-(fluoroacyl)thiochromones. The structure of one of the synthesized compounds was confirmed by X-ray diffraction analysis.     

New fluorinated 1,3-vinylogous amidines as versatile intermediates: synthesis of fluorinated pyrimidin-2(1H)-ones

The condensation of the azaenolates derived from readily available ketimines with fluorinated nitriles offers an efficient and straightforward entry to new fluorinated 1,3-vinylogous amidines. These versatile compounds, in turn, react with triphosgene to yield new fluorinated pyrimidin-2(1H)-ones in high yields.     

Synthesis of dihydrofurans containing trifluoromethyl ketone and heterocycles by radical cyclization of fluorinated 1,3-dicarbonyl compounds with 2-thienyl and 2-furyl substituted alkenes

Manganese(III) acetate based radical cyclization of various fluorinated 1,3-dicarbonyl compounds with 2-thienyl and 2-furyl substituted alkenes produced 3-trifluoroacetyl and 2-trifluoromethyl-dihydrofurans in good yields. The radical cyclizations of 2-methyl-5-[(E)-2-phenylvinyl]furan 2b and 2-[(E)-2-phenylvinyl]thiophene 2c led to the formations of 5-(5-methyl-2-furyl)-4,5-dihydrofuran and 5-(2-thienyl)-4,5-dihydrofuran, respectively. In the reactions of 1,3-dicarbonyls with alkenes, 2-thienyl substituted alkenes formed 4,5-dihydrofurans in higher yields than 2-furyl substituted alkenes.     

Reaction of fluoroalkyl-containing 1,3-dicarbonyl compounds with benzylideneacetone

The reaction of fluoroalkyl-containing 1,3-dicarbonyl compounds with benzylideneacetone with the use of pyridine or triethylamine as a catalyst gave new 3-fluoroalkyl-4-ethoxycarbonyl(acyl)-5-phenylcyclohexan-3-ol-I-ones in yields of 16–33%. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 992–994, May, 1997.     

Reactions of (2,3-dimethylenetetramethylene)bis(dipropylborane) with carbonyl compounds

(2,3-Dimethylenetetramethylene)bis(dipropylborane) (1) prepared by borylation of 2,3-dimethylbutadienediyl dipotassium reacts with ketones to form symmetrical diols in a yield of 46–73%. [4+2]-Cycloaddition reactions of diborane1 with 1,2-dicarbonyl compounds proceed highly stereospecifically, affording onlycis-isomers of 4,5-dimethylenecyclohexane1, 2-diols.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 155–159, January, 1993.     

Reactions of Grignard reagents with 1,3-dicyanoadamantane

Reactions of Grignard reagents RMgX (R = Me, Et, Pr, Bu; X = Br, I) with 1,3-dicyanoadamantane (1) were studied. Optimum conditions for the synthesis of monoaddition products of Grignard reagents to compound 1 were established. The first stage of the reaction of cyanoadamantane 1 with MeMgBr was studied by the MNDO-PM3 method. According to calculations, the more preferable reaction mechanism involves formation of a six-membered cyclic intermediate containing two Mg atoms, two C atoms, and one Br and one N atom.     

Reactions in clusters of acetone and fluorinated acetones triggered by low energy electrons

Electron attachment to clusters of acetone (A), trifluoroacetone (TFA) and hexafluoroacetone (HFA) is studied in a crossed beam experiment with mass spectrometric detection of the anionic products. We find that the electron attachment properties in A change dramatically on going from isolated molecules to clusters. While single acetone is a very weak electron scavenger (via a dissociative electron attachment (DEA) resonance near 8.5 eV), clusters of A capture electrons at very low energy (close to 0 eV). The final ionic products consist of an ensemble of molecules (M) subjected to the loss of two neutral H₂ molecules ((M_n−2H₂)⁻, n ≥ 2). Their formation at low energies can only be explained by invoking new cyclic structures and polymers. In clusters of TFA, anionic complexes containing non-decomposed molecules (M_n⁻) including the monomer (M⁻) and ionic products formed by the loss of one and two HF molecules are observed. Loss of HF units is also interpreted by the formation of new cyclic structures in the anionic system. HFA is a comparatively stronger electron scavenger forming a non-decomposed anion via a narrow resonant feature near 0 eV in the gas phase. In HFA clusters, the non-decomposed parent anion is additionally observed at higher electron energies in the range 3–9 eV. The M⁻ signal carries signatures of self-scavenging processes, i.e., inelastic scattering by one molecule and capture of the completely slowed down electron by a second molecule within the same cluster. The scavenging spectrum is hence an image of the electronically excited states of the neutral molecule.     

聚苯基（聚苄基）甲基硅氧烷的氟烷基化反应研究

通过苯基甲基二乙氧基硅烷和苄基甲基二乙氧基硅烷的缩合反应制备了聚苯基甲基和聚苄基甲基硅氧烷。研究了它们与含氟酰基过氧化物间的反应。经酸碱滴定及ＩＲ、＾１Ｈ ＮＭＲ和＾１９Ｆ ＮＭＲ光谱分析确证反应主要生成苯环上氟烷基取代产物。通过测定经氟烷基化后聚硅氧烷处理的玻璃表面的接触角，初步评价了氟烷基化率对其表现性能变化的影响。     

Scope and limitations of the Julia-Kocienski reaction with fluorinated sulfonylesters

The study of the Julia-Kocienski reaction between fluorinated arylsulfone and ketones is described. The corresponding fluoroalkenes were isolated in moderate to good yields from β- and δ-substituted cyclic ketones. From acyclic ketones and α-substituted cyclic ketones a decarbethoxylation reaction of the sulfonylesters occurred. This decarbethoxylation reaction opened a new route for the preparation of a variety of fluoroalkylsulfones as potential building blocks for the preparation of fluoroalkenes.     

Reactions of 1,3,3,3-tetrafluoro-2-methoxycarbonylpropenesulfenyl chloride with enamines

1,3,3,3-Tetrafluoro-2-methoxycarbonylpropenesulfenyl chloride readily reacts with enamines (derivatives of -oxo acids) to give sulfenylation products. The reactions with N-aryl-substituted enamines are accompanied by cyclization to form N-aryl-2-(2,2,2-trifluoro-1-methoxycarbonylethylidene)-2,3-dihydrothiazoles.     

Synthetic application of fluorinated vinamidinium salts: Synthesis of fluorinated 1,3-butadienylphosphonates by the reaction with Horner-Wadsworth-Emmons reagents

The reaction of β-fluoro vinamidinium salt 1 with Horner-Wadsworth-Emmons reagents (HWE) such as diethyl(ethoxycarbonyl)methylphosphonate (2a), diethyl(methoxycarbonyl)methylphosphonate (2b), diethyl-2-oxopropylphosphonate (2c), diethyl benzylphosphonate (2d), tetraethyl methylenediphosphonate (2e) and diethyl cyanomethylphosphonate (2f) under basic conditions gave the fluorinated 1,3-butadienylphosphonates 3 in moderate to good yields. The phosphonates 3 could be hydrolyzed with a 10% HCl aqueous solution to afford the corresponding γ-(diethylphosphono)-α-fluoro-α,β-unsaturated aldehydes 7 in good yields. The treatment of the phosphonate 3c with an NH₃ aqueous solution at 70 °C produced the pyridine derivative 8 in 60% yield.     

Copper-catalyzed methylation of 1,3-diketones with tert-butyl peroxybenzoate

Copper-catalyzed radical methylation of 1,3-diketones with tert-butyl peroxybenzoate in air is described, providing a general pathway to α-methyl 1,3-diketones in moderate to good yields. This protocol has been scaled up to 50 g, and one of the synthesized products can be used in the synthesis of medicine, Rosuvastatin.     

The relationship between properties of fluorinated graphite intercalates and matrix composition

Inclusion compounds: intercalates of fluorinated graphite matrix with acetonitrile (C₂F_xBr_z·yCH₃CN, x=0.92, 0.87, 0.69 and 0.49, z≈0.01) were synthesized. The kinetics of the thermal decomposition (the 1^st stage of filling→the 2^nd stage of filling) was studied under isothermal conditions. The relationship between intercalates properties and composition and structure of the matrix is discussed. The online version of the original article can be found at     

1,3-Dipolar Addition of Methyl α-Diazoacetoacetate to Enamines： A New Synthetic Route to 5-Amino-4,5-dihydrofurans

The reaction of methyl α-diazoacetoacetate with enamines catalyzed by dirhodium and copper complexes underwent formal 1,3-dipolar addition to give 5-amino-4,5-dihydrofurans in moderate yields. The reaction was suggested to proceed via a nucleophilic addition of enamines to rnetal-carbenes and a subsequent intramolecular cyclization of the resulting zwitterionic intermediates.     

分子内1,3-偶极环加成反应的研究

近几年来,人们对于1,3-偶极环加成反应的理论研究及其在合成上的应用已给予广泛的兴趣和重视。我们曾详细地研究了4-取代苯基(N-4-戊烯基)硝酮的热化学反应性能和其区域选择性以及呋哺偶极体系的热和光化学反应。本文进一步探讨了取代基效应对环加成反应的影响,利用色谱法定量地研究了取代基的电子效应与区域选择性间的关系,并对肉桂醛肟的构型及有关的反应作了研究。     

Unusual O-conjugate addition reactions of β-ketoesters and 1,3-diketones to ethyl propynoate: applications to the synthesis of furans

Divinyl ethers were synthesized from 1,3-dicarbonyl compounds. Reactions of β-ketoesters and 1,3-diketones with ethyl propynoate in the presence of N-methylmorpholine produced unusual O-conjugate addition products in good yields. The divinyl ethers derived from 1,3-diketones were utilized for the synthesis of 2,3,5-trisubstituted furans under the standard radical cyclization conditions.     

A facile synthesis of fluorinated alkoxytrimethylsilanes using 1-methylimidazole as an acid scavenger

Fluorinated alkoxytrimethylsilanes (R_fCH₂OSiMe₃), potential candidates for the third-generation cleaning agents, were synthesized in high yields over 95% from the reaction of chlorotrimethylsilane and fluorinated alcohol (R_fCH₂OH) in the presence of 1-methylimidazole. Elemental and ¹H NMR spectroscopic analysis showed that the reaction proceeds through the formation of an intermediate, 3-methyl-1-trimethylsilylimidazolium chloride.     

Synthesis and characterization of fluorinated polyurethane with fluorine-containing pendent groups

A novel fluorinated polyurethane （FPU） with fluorine-containing pendent groups was prepared by using fluorinated polyether glycol （PTMG-g-HFP） as a soft segment, 1,6-hexamethylene diisocyanate （HDI） or toluene diisocyanate （TD1） as a hard segment and 1,4-butanodiol （BDO） as a chain extender. FTIR, ^1H NMR, ^13C NMR and GPC were used to characterize the structure of the fluorinated polyurethane. Thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by TGA. XPS analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. The results showed the fluorine enrichment on the surface of FPU.     

Simple,One-Pot,and Three-Component Coupling Reactions of Azaarenes (Phenanthridine,Isoquinoline, and Quinoline), with Acetylenic Esters Involving Methyl Propiolate or Ethyl Propiolate in the Presence of NH-Heterocyclic or 1,3-Dicarbonyl Compounds

Three-component reactions involving azaarenes (quinoline, isoquinoline, and phenanthridine) with acetylenic esters such as methyl propiolate or ethyl propiolate in the presence of NH-heterocyclic compounds (carbazole, maleimide, 5-nitroindazole, 2-benzoxazolinone, indole, and 2-methylindole) or 1,3-dicarbonyl compounds involving acetylacetone and N,N′-dimethylbar bituric acid are described. The reactions proceeded smoothly at room temperature without a catalyst and with excellent yields. This method is very useful for functionalizing aza-aromatic compounds in a one-pot operation.