10605-46-6Relevant academic research and scientific papers
The influence of crown ethers on the kinetics of E1cB and E2 β-elimination reactions of di(4-nitrophenyl)fluoroethanes with sodium methoxide in methanol
Leffek, Kenneth T.,Schroeder, Grzegorz
, p. 3077 - 3080 (1982)
The addition of crown ethers 1,4,7,10,13 pentaoxacyclopentadecane (15C5)and 1,4,7,10,13,16-hexaoxacyclooctadecane (18C6) in quantities equimolar to the base, to β-elimination reactions of 1,1,1-trifluoro-2,2-di(4-nitrophenyl)ethane and 1-fluoro-2,2,di(4-n
Synthesis of 2,2-diarylvinyl phenyl selenides by dehydration of 2-hydroxyalkyl phenyl selenides
Stuhr-Hansen, Nicolai
, (2018/10/20)
A novel route to 2,2-diarylvinyl phenyl selenides is reported by dehydration of the corresponding 2,2-diaryl-2-hydroxyethyl phenyl selenides, prepared by oxyphenylselenenylations of the corresponding 1,1-diarylethylenes, upon treatment with p-toluenesulfonic acid.
Effect of immobilization on catalytic characteristics of saturated Pd-N-heterocyclic carbenes in Mizoroki-Heck reactions
Aksin, ?zge,Türkmen, Hayati,Artok, Levent,?etinkaya, Bekir,Ni, Chaoying,Büyükgüng?r, Orhan,?zkal, Erhan
, p. 3027 - 3036 (2007/10/03)
A saturated Pd-N-heterocyclic complex was immobilized on an amorphous silica. The complex itself is of very high thermal stability. However, TEM observations, hot filtration, reusability, and poisoning tests all revealed that the complex acted only as a precatalyst to highly active Pd species in Mizoroki-Heck reactions when immobilized. The complex appears more stable when used under homogeneous reaction conditions. The immobilized complex afforded high turnover numbers, 104-105. The higher turnover frequencies were realized at the lower Pd concentrations, which is a characteristic property of ligand-free Pd catalyzed reactions.
Nucleosides. Part LXIV. Base-Labile Protecting Groups for the Oligoribonucleotide Synthesis
Muench, Ursula,Pfleiderer, Wolfgang
, p. 1504 - 1517 (2007/10/03)
New labile protecting groups for the anticipated synthesis of oligoribonucleotides were developed and introduced via their carbonochloridates 8-11 at the 5'-O position of thymidine (15) to form 16, 18, 21, and 24 in good yields (Schemes 2 and 3). Similarly, the 5'-O-diphenylphosphinoyl(dpp)-protected thymidine derivative 27 was synthesized with diphenylphosphinoyl chloride 14 as the reactive reagent. With the help of the model compounds 16, 18, 21, 24, and 27, the deprotection rates of these functions towards base treatment were recorded to evaluate their usefulness as temporary protecting groups in RNA assembly (Table). Finally, the relative stability of the 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) protecting group towards bases confirmed its use as a permanent blocking group in our npe/npeoc strategy.
Synthesis and double olefin extrusion of 2,2,6,6-tetraaryl-1,5-dioxa-4λ5-phosphaspiro[3.3]heptanes
Kawashima, Takayuki,Okazaki, Rei,Okazaki, Renji
, p. 379 - 386 (2007/10/03)
The title compounds were synthesized by cyclization and dehydration of the corresponding bis(β-hydroxyalkyl)phosphine oxides with Appel's reagent. Since these compounds were very moisture sensitive to hydrolyze to the starting bis(β-hydroxyalkyl)phosphine oxides except for tetrakis(4-nitrophenyl) derivative, their in-situ generation and thermolysis were carried out to give two molar equivalents of the corresponding olefins in good yield in sharp contrast to tetrakis(trifluoromethyl) derivative.
Substituent-Dependent Electron-Transfer Induced Photooxygenation of 1,1-Diarylethylenes
Gollnick, Klaus,Schnatterer, Albert,Utschick, Gerald
, p. 6049 - 6056 (2007/10/02)
Rates and products of 9,10-dicyanoanthracene-sensitized photooxygenations of 1,1-diarylethylenes (1a-r) in acetonitrile were studied.If at least one of the aryl groups carries an electron-donating substituent at the para (or ortho) position (1a-l), 3,3,6,6-tetraaryl-1,2-dioxanes (2a-l) are generated in high yields (85-100percent).Benzophenones (3) are the only other observable products. 1,1-Diphenylethylene (1n) and its m-methoxy (1m), p-chloro (1o,p), and p-nitro (1q,r) derivatives, however, yield mainly benzophenones (3m-r) (>50percent) (the p-nitro compounds only in the presence of biphenyl). 1,2-Dioxanes (2m-p), cyclobutanes (4n-p), and α-tetralones (5m-o) are obtained as side products.Dioxanes, benzophenones, and α-tetralones are products of electron-transfer induced oxygenations involving triplet ground-state molecular oxygen, 3O2.Singlet molecular oxygen, O2(1Δg), contributes to the benzophenone formation from strongly electron-donor substituted diarylethylenes.An exception is the most powerful electron-donor substituted diarylethylene 1a, with which O2(1Δg) undergoes an electron-transfer reaction affording dioxane 2a.Dioxane formation proceeds via free-radical cations 1.+, which enter into a chain reaction with 1, 3O2, and another molecule of 1 to yield dioxane 2 and a new radical cation 1.+ that maintains the chain reaction.The efficiency of this chain process, however, is found to be several orders of magnitude smaller than expected.To explain this result, a 1,6-biradical .1-1-O2. is proposed to be generated in this chain reaction as the product-determining intermediate that predominantly fragments into 3O2 and two molecules of 1.Cyclization to dioxane 2 and transformation to benzophenone 3 occur at presumably less than 0.1percent from this biradical.The pathways leading to cyclobutanes (4) and α-tetralones (5) are also discussed.
Models for intramolecular exchange in organic π-conjugated open-shell systems. A comparison of 1,1-ethenediyl and carbonyl linked bis(arylnitrenes)
Ling, Chris,Minato, Masaki,Lahti, Paul M.,Van Willigen, Hans
, p. 9959 - 9969 (2007/10/02)
Linkage of two phenylnitrene electron-spin-bearing units by exchange coupling linker groups leads to model open-shell π-conjugated systems of the general structure :N-Ph-X-Ph-N: of various possible connectivity types. Use of variable-temperature electron
A base labile protecting group for peptide synthesis: 2,2,-Bis(4'-nitrophenyl)ethan-1-oxycarbonyl urethanes
Ramage,Blake,Florence,Gray,Raphy,Roach
, p. 8001 - 8024 (2007/10/02)
A base labile urethane (Bnpeoc) group derived from 2,2,-bis(4'-nitrophenyl)ethan-1-ol has been developed as an amine protecting group. This protecting group may be cleaved using the reagents DBN, DBU, DBU/HOAc and piperidine. The preparations of N(α)-Bnpeoc amino acids and applications to peptide/glycopeptide synthesis are described.
The reinvestigation of the kinetics of the reactions of fluorodi(4-nitrophenyl)ethanes with sodium methoxide in methanol
Leffek, Kenneth T.,Schroeder, Grzegorz
, p. 1696 - 1701 (2007/10/02)
The procedure previously described for the preparation of 1-fluoro-2,2-di(4-nitrophenyl)ethane actually yields 1,1,2-tri(4-nitrophenyl)ethane.Fluoro-2,2-di(4-nitrophenyl)ethane has been prepared and rate constants, isotope effects, and activation parameters for the β-elimination reaction with methoxide ion in methanol are reported.These parameters indicate a concerted E2 mechanism, with a fairly symmetrical transition state.The subsequent dimerization reaction of the olefin product to yield 1,1,3,3-tetra(4-nitrophenyl)butene-1 is described.The reaction of 1,1,1-trifluoro-2,2-di(4-nitrophenyl)ethane with methoxide ion in methanol has been reinvestigated and the reaction on the first product 1,1-difluoro-2,2-di(4-nitrophenyl)ethylene with excess methoxide, to give di(4-nitrophenyl)ketene dimethylacetal in a multistep reaction, is reported.
