1694-22-0Relevant articles and documents
Exploratory studies toward a synthesis of flavaglines. A novel access to a highly substituted cyclopentenone intermediate
Basmadjian, Christine,Zhao, Qian,Désaubry, Laurent
, p. 727 - 730 (2015)
The gold(I)-catalyzed intramolecular siloxycyclization developed by Rhee and collaborators was shown to operate also on alkyl ethers to generate a highly substituted 2-cyclopentenone 8, extending the application of this reaction. Conversion of 8 to known anticancer natural products following a reported strategy was examined.
The Evolution of the Total Synthesis of Rocaglamide
Zhou, Zhe,Dixon, Darryl D.,Jolit, Anais,Tius, Marcus A.
, p. 15929 - 15936 (2016/10/24)
The complex flavagline, (?)-rocaglamide, possesses a synthetically intriguing tricyclic scaffold with five contiguous stereocenters and also exhibits potent anticancer, anti-inflammatory and insecticidal activity. This full account details distinct approaches to (±)- and (?)-rocaglamide utilizing Br?nsted acid catalyzed and asymmetric Pd0-catalyzed Nazarov chemistry developed in our laboratory, respectively. The successful asymmetric synthesis revealed unforeseen mechanistic complexity that required adjusting our strategy to overcome an unanticipated racemization process, an unusual reversible ring-cleavage step and a very facile trialkylsilyl group migration.
Synthesis of 2-(hetero)aryl-5-(trimethylsilylethynyl)oxazoles from (hetero)arylacrylic acids
Pankova, Alena S.,Stukalov, Alexander Yu.,Kuznetsov, Mikhail A.
, p. 1826 - 1829 (2015/04/27)
A three-step method for the synthesis of 2-(hetero)aryl-5-(trimethylsilylethynyl)oxazoles is described. Easily accessible bis(trimethylsilyl)acetylene and acrylic acid derivatives are used as starting materials for the preparation of mono- and disubstituted 5-(trimethylsilyl)pent-1-en-4-yn-3-ones. Oxidative phthalimidoaziridination of these enynones provides the key 2-acyl-1-phthalimidoaziridines that are further utilized in the thermal expansion of the three-membered ring to furnish the target functionalizable oxazoles.
Synthesis of each enantiomer of rocaglamide by means of a palladium(0)-catalyzed nazarov-type cyclization
Zhou, Zhe,Tius, Marcus A.
supporting information, p. 6037 - 6040 (2015/05/13)
A recently reported Pd0-catalyzed asymmetric Nazarov-type cyclization has been successfully applied in the key step of the first catalytic asymmetric total synthesis of (-)-rocaglamide (natural) and (+)-rocaglamide. The stereochemistry at the C3 position that controls the stereochemistry of all other stereocenters is determined in the cyclization step. This versatile and modular synthesis proceeds from simple reagents.
Reactions of chlorine substituted (E)-2,3-diphenylpropenoic acids over cinchonidine-modified Pd: Enantioselective hydrogenation versus hydrodechlorination
Szllsi, Gy?rgy,Hermán, Beáta,Szabados, Erika,Fül?p, Ferenc,Bartók, Mihály
experimental part, p. 28 - 36 (2011/02/24)
The effect of the chlorine position on the C-Cl bond hydrogenolysis and the enantioselective hydrogenation of Cl substituted (E)-2,3-diphenylpropenoic acid derivatives has been studied over cinchonidine-modified Pd/Al2O 3. In contrast to the fast hydrodechlorination of the β-phenyl-para-Cl substituted acids the Cl on the α-phenyl ring was barely hydrogenolized. These observations were interpreted by the different arrangements of the two phenyl rings on the surface, with the α- and β-phenyl rings adsorbed tilted and parallel, respectively. The results confirmed the beneficial effect of the α-phenyl-ortho-substituents on the chiral discrimination, thus the 2,3-diphenylpropionic acids substituted by Cl on the α-phenyl ring could be prepared in good yields and optical purities. The conclusions were used for the rational design of an acid, i.e. (E)-2-(2-methoxyphenyl)-3-(3,4-difluorophenyl)propenoic acid, which afforded the best optical purity (ee up to 95% at 295 K) described until now in this heterogeneous system.
1,5-Electrocyclisation of azomethine ylides leading to pyrrolo[2,1-a] isoquinolines - Concise construction of the lamellarin skeleton
Nyerges, Miklós,Toke, László
, p. 7531 - 7534 (2007/10/03)
A new, general route to the 1,2-diaryl-substituted pyrrolo[2,1-a] isoquinolines has been developed via the 1,5-dipolar electrocyclisation reactions of azomethine ylides derived from readily available stilbenic acid derivatives. This method was applied to the concise construction of a lamellarin skeleton.
Design and synthesis of some new α-phenyl cinnamoyl derivatives for selective protection of purine nucleosides
Tripathi, Snehlata,Misra, Krishna,Sanghvi, Yogesh
, p. 3069 - 3081 (2007/10/03)
Three new α-phenylcinnamic acid derivatives [4-methoxy-α- phenylcinnamic acid, α-(4-methoxyphenyl)-cinnamic acid, and 4,4′-bismethoxy-α-phenylcinnamic acid] were synthesized, characterized, and selectively used for protecting the exocyclic amino function of purine nucleosides (2′-deoxyadenosine and 2′-deoxyguanosine) via active ester generation. The acids were first activated using p -nitrophenol, and these activated esters were used subsequently for the selective protection of amino groups. The N -protected derivatives of 2′-deoxyguanosine and 2′-deoxyadenosine have been found to be sufficiently stable toward acids, thus minimizing depurination under oligodeoxyribonucleotide synthesis protocol. The ease of syntheses of N -protected purine nucleosides, their stability under an acidic environment, and mild deprotection conditions are the key advantages of the new protecting groups. Copyright Taylor & Francis, Inc.
Reactions of carbonyl compounds in basic solutions. Part 34. The mechanism of the base-catalysed ring fission of 2,3-diphenylcycloprop-2-en-1-one
Bowden, Keith,Burgess, Emma J.
, p. 1594 - 1600 (2007/10/03)
The rate coefficients for the base-catalysed ring fission of a series of 2-phenyl-3-(2-, 3-or 4-substituted phenyllcycloprop-2-en-1-ones to give the corresponding (E)-2,3-diphenylacrylic acids have heen determined in water at 30.0 °C, as well as for the unsubstituted compound at 40.0, 50.0 and 60.0 °C. The effects of meta-and para-substituents on the rates have been correlated using the Hammett equation to give a reaction constant, p, equal to ca 1.2 at 30 °C. For the unsubstituted compound, the activation parameters have been calculated and the kinetic solvent isotope effect has been studied. The effects of ortho-substituents on the rates appear to be mainly polar, rather than steric, in origin. The evidence indicates a mechanistic pathway which proceeds by addition of hydroxide anion to the ketone, which is rate-determining. The adduct suffers ring fission to give the final product via a carbanionic intermediate.
Effect of substituents on the 13C NMR chemical shifts of para-substituted α-phenyl-β-pyridylacrylic acids
Jovanovi?,Mi?i?-Vukovi?,Drmani?,?anadi
, p. 39 - 41 (2007/10/03)
The 13C NMR spectra of para-substituted α-phenylcinnamic and 3- and 4-pyridylacrylic acids, with a wide range of substituents effects, were determined in deuterated dimethylsulfoxide (DMSO-d6). The effect of substituents in both the α-phenyl and β-pyridine groups in these acids is investigated using linear free energy relationships and multiple regression analysis as applied to 13C NMR chemical shifts of the C(α) and C(β) of the ethylenic bond and the carboxylic group carbon. Dissection of the α-phenyl substituent effects into the inductive and resonance components, using the dual substituent parameter (DSP) method, points to a blend of inductive and resonance effects in the π-electronic system.
Reaction of α,β-Unsaturated Carboxylic Acids with Manganese(III) Acetate in the Presence of Chloride Ion
Yonemura, Hiroshi,Nishino, Hiroshi,Kurosawa, Kazu
, p. 3153 - 3160 (2007/10/02)
The reaction of 3-phenylpropenoic acids with manganese(III) acetate - Cl- complex yielded 1,2,2-trichloro-1-phenylethanes, 1-acetoxy-2,2-dichloro-1-phenylethanes, and 2,2-dichloro-1-phenylethanols. (E)-2,3-Diphenylpropenoic acids gave 2,2-dichloro-1,2-diphenylethanones and 2-acetoxy-1,2-diphenylethanones. 3,3-Diphenylpropenoic acids yielded 2,2-dichloro-1,1-diphenylethenes, 1-acetoxy-2,2-dichloro-1,1-diphenylethanes, 2,2-dichloro-1,1-diphenyl-1-ethanols, and 2-hydroxy-2,2-diphenylethanal.Fluorenylideneacetic acid gave 9-chloro-9-(dichloromethyl)fluorene, 9-acetoxy-9-(dichloromethyl)fluorene, and 9-fluorenone. 1-Cyclohexenecarboxylic acid yielded 1,2-dichlorocyclohexanecarboxylic acid and 1-acetoxy-2-chlorocyclohexanecarboxylic acid.The reaction can be explained in terms of a free-radical mechanism involving manganese(III) acetate - Cl- complexation, addition of Cl. radical, decarboxylation, and the oxidation of chloroethenes which are the reaction intermediates.
