共查询到20条相似文献,搜索用时 31 毫秒
1.
Benzamides with tethered acetal groups undergo reactions in CF3SO3H to give ring-fused isoindolinones by a cyclization cascade. The reaction initially forms an N-acyliminium ion which then gives the isoindolinone by the aza-Nazarov reaction. An unusual variant also cyclizes at the allylic position. 相似文献
2.
《Mendeleev Communications》2023,33(3):397-400
One-pot acid-catalyzed cyclocondensation of 2-methyl-resorcinol with 4-(propargyloxy)benzaldehyde in CHCl3/CF3CO2H media affords all-cis (rccc) and/or cis-trans-trans (rctt) calix[4]resorcinol diastereomers bearing four terminal alkyne groups at aromatic substituents, the isomer ratio and yield being dependent on the CHCl3/CF3CO2H ratio. The rctt isomer (kinetic control product) can be converted to thermodynamically more stable rccc isomer at prolonged refluxing in CHCl3/CF3CO2H mixture. The rccc diastereomer was subjected to additional propargylation followed by the click reactions with benzylic azides to afford new highly triazolated calix[4]resorcinols. 相似文献
3.
Kristína Csatayová James A. Lee Kenneth B. Ling Paul M. Roberts Angela J. Russell James E. Thomson 《Tetrahedron》2010,66(43):8420-8440
A highly chemo- and diastereoselective protocol for the cyclopropanation of tertiary allylic amines with Shi’s carbenoid [CF3CO2ZnCH2I] is described. The high levels of diastereoselectivity observed in these reactions may be attributed to chelation of the nitrogen atom to the zinc reagent, which then transfers a methylene unit to the syn-face of the olefin. Furthermore, a stereodivergent protocol for the cyclopropanation of a range of allylic carbamates has been developed, which provides access to both diastereoisomers of the corresponding cyclopropanes with very high levels of diastereoselectivity: cyclopropanation with the Wittig-Furukawa reagent [Zn(CH2I)2] proceeds under chelation control to give the corresponding syn-product, whilst reaction with Shi’s carbenoid proceeds under steric control to give the corresponding anti-cyclopropane, in >95:5 dr in both cases. 相似文献
4.
Good -stereoselectivity is observed in the epoxidation of allylic silyl ethers with CF3CO3H, indicating a new type of hydrogen-bonded transition state. 相似文献
5.
A study of the decomposition mechanisms of peroxydodecanoic (RCO3H) and perbenzoic (φCO3H) acids in cyclohexane at both reflux temperature and less than reflux temperature (i.e. with and without dissolved oxygene) and comparisons of all the products from these reactions with those obtained from the decomposition of dodecanoyl- and benzoyl-peroxydes under the same conditions, leads to the following conclusions: (a) in both cases there is a radical mechanism, the initiating step being the rupture of the O-O bonds giving RCO2 and φCO2, (b) under reflux (i.e. without oxygen) the radical RCO2 undergoes rapid decomposition and the resulting R- gives rise to a chain reaction leading to the alcohol ROH. The φCO2 radical undergoes much slower decomposition and through chain transfer with the solvent produces φCO2H and cyclohexanol. These reactions are fast; (c) at less than reflux temperature (i.e. in presence of dissolved oxygen) R radicals or S (solvent) radicals combine with the oxygen giving peroxy and oxy radicals. These species are electrophilic and therefore do not lead to the breaking of the O-O bond of the peracid. Rather, the acid hydrogen is attacked, giving RCO3 or φCO3, radicals. Through a series of reactions involving aldehyde intermediates, the corresponding carboxylic acids are obtained. These reactions are much slower than those at reflux temperature. 相似文献
6.
Practical and efficient catalytic asymmetric allylic transfer reactions of tin reagents promoted by BINOL-Ti[OCH(CF3)2]2 complex by the utilization of t-BuSBEt2 are successful with a variety of functionalized aldehydes containing ketone, aldehyde, ester, amide, or carbamoyl functionality and affords products in high levels of enantioselectivity. 相似文献
7.
The CO_2 laser induced room temperature reactions of CH_3CF_2H or another protium-donorCH_3CHClCH_3 with chlorine-atom donors (Z--Cl) CFCl_2CF_2Cl, CF_3CCl_3, CFCl_3 or CF_2Cl_2, havebeen investigated. Some of these reactions can yield two important monomers (CF_2=CH_2 andCF_2=CFCl) for fluoropolymers simultaneously. The yield dependence of these two alkenes on experi-mental conditions has been studied. A laser-initiated chain process is supported by identifica-tion of Z--H intermediates in these reactions. 相似文献
8.
Xizhen Zhu Kevin D. Kreutter Huaping Hu Mark R. Player Micheal D. Gaul 《Tetrahedron letters》2008,49(5):832-834
A novel reagent combination, Tf2O/Na2CO3·1.5H2O2, has been developed for the oxidation of highly electron deficient pyridines to their corresponding N-oxides. The N-oxidation reaction, utilizing the in situ generated peracid, proceeds under mild conditions that allow for a number of functional groups and substitution patterns on the pyridine ring. 相似文献
9.
Orienting Effect of the Cage Addends: The Case of Nucleophilic Cyclopropanation of C2‐C70(CF3)8
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Marina G. Apenova Olesya O. Semivrazhskaya Eugenia V. Borkovskaya Nikita M. Belov Dr. Ilya N. Ioffe Dr. Vitaliy Yu. Markov Prof. Dr. Sergey I. Troyanov Dr. Natalia S. Lukonina Prof. Dr. Lev N. Sidorov Dr. Alexey A. Goryunkov 《化学:亚洲杂志》2015,10(6):1370-1378
C2‐C70(CF3)8 was found to be a very promising substrate in the Bingel and the Bingel–Hirsch reactions combining perfect regioselectivity with much higher reactivity compared to its analogs. The reactions with diethyl malonate yield a single isomer of the monoadduct C70(CF3)8[C(CO2Et)2] and a single C2‐symmetrical bisadduct C70(CF3)8[C(CO2Et)2]2. The Bingel–Hirsch variation is particularly interesting in that it additionally affords, in a similar regioselective manner, the unexpected alkylated derivatives C70(CF3)8[CH(CO2Et)2]H and C70(CF3)8[C(CO2Et)2][CH(CO2Et)2]H. The novel compounds have been isolated and structurally characterized by means of 1H and 19F NMR spectroscopy as well as single‐crystal X‐ray diffraction. The mechanistic and regiochemical aspects of the reaction are explained with the aid of DFT calculations. 相似文献
10.
Tadashi Narita Hiroshi HamanaMasato Takeshita Hiroshi Nakagawa 《Journal of fluorine chemistry》2002,117(1):67-71
Radical polyaddition of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate [CF2C(CF3)OCOC6H4COOC(CF3)CF2] (BFP) with diformylalkanes to produce fluorinated polymer bearing ketone-carbonyl groups in main chain is described. The radical additions of hexanal, pentanal and benzaldehyde with 2-benzoxypentafluoropropene [CF2C(CF3)OCOC6H5] were examined as model reactions to yield the corresponding addition product with hexanal and pentanal in high yields, and no product with benzaldehyde. The addition of acyl and hydrogen was found to take place to perfluoroisopropenyl group. The results of the model reactions suggested that the reaction might be applicable to polyaddition to produce polymers with diformylalkanes. The results of polyaddition of BFP with glutaraldehyde under the emulsion polymerization condition showed that the polymer of Mn=4.8×103 was obtained in fairly high yields. This might be a novel preparation method of polymers bearing fluorinated polyketone structure. 相似文献
11.
Yoko Hamada Rio Matsunaga Tomoko Kawasaki-Takasuka Takashi Yamazaki 《Molecules (Basel, Switzerland)》2021,26(14)
We have previously clarified that the strongly electron-withdrawing CF3 group nicely affected the base-mediated proton shift of CF3-containing propargylic or allylic alcohols to afford the corresponding α,β-unsaturated or saturated ketones, respectively, which was applied this time to the Claisen rearrangement after O-allylation of the allylic alcohols with a CF3 group, followed by isomerization to the corresponding allyl vinyl ethers via the proton shift, enabling the desired rearrangement in a tandem fashion, or in a stepwise manner, the latter of which was proved to have attained an excellent diastereoselectivity with the aid of a palladium catalyst. 相似文献
12.
A density functional theory study of dimers of hydrophosphoryl compounds and proton transfer in them
Yu. V. Babin A. V. Prisyazhnyuk Yu. A. Ustynyuk 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(1):94-100
The structures of dimers of several types of dimethylphosphinous acid (CH3)2POH and dimethylphosphine oxide (CH3)2P(O)H and dimers of the corresponding perfluorinated derivatives (CF3)2POH and (CF3)2P(O)H were studied in detail by density functional theory with the PBE gradient-corrected functional and the TZ2p basis set. Fairly strong dimeric associates (2.50–10.5 kcal/mol) were shown to form thanks to O-H···O, O-H···P, and C-H···O H-bonds and dipole-dipole interactions of polar phosphoryl groups P → O of two monomer molecules. The existence of C-H···O and the absence of P-H···O H-bonds in (CH3)2P(O)H dimers was substantiated by an AIM (atoms in molecules) analysis of their structures according to Bader. The reaction coordinates were calculated for synchronous transfer of two protons in (CH3)2POH and (CF3)2P(O)H dimers. Both rearrangements were shown to occur via symmetrical six-membered planar transition states with activation barriers of less than 20 kcal/mol, which was much lower than for intramolecular transfer in the corresponding monomers (47 kcal/mol for the (CH3)2P(O)H → (CH3)2POH pair). The tautomeric transitions between the phosphinous acid and phosphine oxide forms observed experimentally in nonpolar media under mild conditions in the absence of molecules that could act as proton carriers were shown to proceed as bimolecular reactions with the intermediate formation of the corresponding dimers. 相似文献
13.
Y. Amimoto R.N. Haszeldine M. Maruta W.D. Morton R. Rowland 《Journal of fluorine chemistry》1980,16(6):552
Routes to perflouroallyl chloride, CF2:CF.CF2Cl, and to -and -1-chloro-hexafluoro-2-trifluoromethyl(but-2-ene), (CF2Cl)(CF3)C:CF.CF3 are reported, and their susceptibility to attack by nucleophiles discussed; the allylic chlorine atoms in these olefins are the controlling factor in determining the products obtained.The conversion of 3-chloropentafluoropropene into a series of perfluoroallyl derivatives of general formula R.CF2.CF:CF2 [R = (CF3)3C-, CF3O-, C6F5-, l-, MeO-, etc.] is described, and the further chemistry of 3-chloropentafluoropropene and its derivatives outlined.Water reacts rapidly with (CF2Cl)(CF3)C:CF.CF3 to give CF2:C(CF3).CFCl.CF3 or CF3.CO.CH2.CF3. Methanol affords CF2:C(CF3).CFOMe.CF3 and (MeOCF2)(CF3)C:CF.CF3 as initial products, with subsequent secondary products such as CF3.CFOMe.CH(CF3).CF2OMe, (CF3)(MeO)C:C(CF3).CF3OMe, MeO.CF:C(CF3).CFOMe.CF3, (CF3)(MeO)CF.CH(CF3).CO2Me, and (CF3)(MeO)C:C(CF3).CO2Me. The influence of allylic chlorine and of reaction time on the formation of these products, and mechanistic pathways for their formation are considered. 相似文献
14.
The reactions of hydrogen atoms produced by the mercury-photosensitized decomposition of H2 with bis(trifluoromethyl)disulfide has been studied. The rate coefficient for the primary reaction, H + CF3SSCF3 → CF3SH + CF3S, was determined in competition with the reaction H + C2H4S → SH + C2H4 to have the value k = (3.0 ± 0.18) × 1014 exp[-(4560 ± 140)/RT] cm3 mol?1 S?1. The high A factor can be partially accounted for by assuming free rotation for the two CF3 groups and the SCF3 groups about the S—S bond in the transition state. The relatively high activation energy is attributed to inductive and orbital overlap effects. CH3SH, H2S, and CF3SH all react with CF3SSCF3 to yield solid complexes which were not explored further. 相似文献
15.
The condensation of 2-aminoacetophenone with RFCO2Et (RF = CF3, CF2H, CF2CF2H) in the presence of LiH in THF or ButOK in ButOH affords either 2-polyfluoroalkyl-4-quinolones or 1-(2-polyfluoroacylaminophenyl)-3-polyfluoroalkylpropane-1,3-diones, depending on the ratio of the initial reactants. The latter are hydrolyzed in an acidic medium to produce 2-polyfluoroalkyl-4-quinolones. N-Methyl-2-trifluoromethyl-4-quinolone was synthesized from 2-aminoacetophenone, CF3CO2Et, and MeI in the presence of ButOK. 相似文献
16.
Kozitsyna N. Yu. Martens M. V. Stolyarov I. P. Gekhman A. E. Vargaftik M. N. Moiseev I. I. 《Russian Chemical Bulletin》1999,48(9):1673-1681
The effects of the solvent and the ligand chirality on the regioselectivity of oxidative esterification of propylene and cyclohexene
by PdII carboxylates were studied using achiral (MeCO2
−, Me2CHCH2CO2
−), racemic ((±)-CF3CF2CF2OC*F(CF3)CO2
−), and chiral ((S)−(+)−MeC*H(Et)CO2
−, (+)−CF3CF2CF2OC*F(CF3)CO2
−) carboxylate ligands. The oxidation of alkenes in aprotic media (CHCl3, CH2Cl2, CO2, THF) affords mainly allylic esters (in the case of cyclohexene also homoallylic esters) and the oxidative esterification
at the vinylic position is absent. In weakly solvating media (CHCl3, CH2Cl2) the regioselectivity of cyclohexene oxidation (the allyl to homoallyl ratio) increases substantially on going from achiral
or racemic acido ligands to chiral acido ligands. In a more donor medium (THF) the ligand chirality effect almost vanishes.
The effects of the ligand chirality and the nature of the solvent on the mechanism of alkene oxidation by PdII complexes are discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1695–1703, September, 1999. 相似文献
17.
O-Nitrosobis(trifluoromethyl)hydroxylamine gives novel reactions with tris(trifluoromethyl)-phosphine, -arsine and -stibine to affford mainly the corresponding bis(trifluoromethyl)nitroxol derivatives. Tris(trifluoromethyl) phosphine affords (CF3)2NOP(O)(CF3)2 and (CF3)2NNO. Tris(trifluoromethyl) arsine also gives (CF3)2NNO in high yield, together with smaller amounts of (CF3)2NOAs(CF3)2, CF3NCF2, COF2 and a polymeric white solid. With tris(trifluoromethyl)stibine, no oxidation nor addition reactions occurred. Instead, [(CF3)2NO]3Sb and [(CF3)NO]2SbCF3 were obtained in high yields. The stoichiometry of the reactions suggests that the additional amounts of bis(trifluoromethyl)nitroxyl groups bonded to antimony are derived from the trifluoromethyl groups bonded to antimony. Mechanisms to rationalise these reactions are proposed. 相似文献
18.
Summary of main observation and conclusion CF3S,CF3 and HCF2 groups have been identified as valuable functionalities for drug development.Despite significant accomplishments in the trifluoromethylthiolation,trifluoromethylation and d讦luoromethylation reactions,directly converting common functional groups into CF3S,CF3 or HCF2 groups is still highly desirable. 相似文献
19.
Spiro orthoesters give poly(cyclic orthoester)s by single ring-opening polymerization in the presence of acid catalysts, and this process undergoes the equilibrium polymerization. We have applied the function of equilibrium polymerization to chemical recycling of polymeric materials. Crosslinked poly(cyclic orthoester)s, prepared by radical additions of poly(cyclic orthoester)s possessing exomethylene groups and dithiols, efficiently decrosslinked to bifunctional spiro orthoesters in the presence of CF3CO2H in CH2Cl2. The dithiol-linked bifunctional spiro orthoester monomers, prepared by the radical additions of spiro orthoester possessing exomethylene group and dithiols, afforded the corresponding crosslinked polymers in the presence of CF3CO2H as a catalyst in bulk. The decrosslinking of the obtained crosslinked polymer proceeded quantitatively to obtain the corresponding bifunctional monomer at room temperature in CH2Cl2. Further, an acid-catalyzed reversible crosslinking-decrosslinking of a polymer having a spiro orthoester group in the side chain was carried out. The copolymer obtained by the radical copolymerization of 2-methylene-1,4,6-trioxaspiro[4.6]undecane with acrylonitrile was treated with CF3CO2H at −10 °C in CH2Cl2 to afford the crosslinked polymer quantitatively. The crosslinked polymer was then treated with CF3CO2H at room temperature at a low concentration in CH2Cl2 to recover the original polymer. 相似文献
20.
M. S. Klenov A. M. Churakov Yu. A. Strelenko V. A. Tartakovsky 《Russian Chemical Bulletin》2011,60(10):2051-2056
A new method for the synthesis of benzotetrazine-1,3-dioxides was developed from the 2-(tert-butyl-NNO-azoxy)-N-nitroaniline O-alkyl derivatives upon the action of strong acids (H2SO4, MeSO3H, CF3CO2H) or BF3·Et2O. A mechanism suggested for these reactions includes transformation of the N=N(O)OR group (R = Me, Pri) to the oxodiazonium ion (N=N=O)+, which intramolecularly reacts with the neighboring tert-butyl-NNO-azoxy group, furnishing the tetrazine-1,3-dioxide ring. 相似文献