17206-54-1Relevant articles and documents
Synthetic Applications and Mechanistic Studies of the Hydroxide-Mediated Cleavage of Carbon-Carbon Bonds in Ketones
Mazziotta, Andrea,Makarov, Ilya S.,Fristrup, Peter,Madsen, Robert
, p. 5890 - 5897 (2017/06/07)
The hydroxide-mediated cleavage of ketones into alkanes and carboxylic acids has been reinvestigated and the substrate scope extended to benzyl carbonyl compounds. The transformation is performed with a 0.05 M ketone solution in refluxing xylene in the presence of 10 equiv of potassium hydroxide. The reaction constitutes a straightforward protocol for the synthesis of certain phenyl-substituted carboxylic acids from 2-phenylcycloalkanones. The mechanism was investigated by kinetic experiments which indicated a first order reaction in hydroxide and a full negative charge in the rate-determining step. The studies were complemented by a theoretical investigation where two possible pathways were characterized by DFT/M06-2X. The calculations showed that the scission takes place by nucleophilic attack of hydroxide on the ketone followed by fragmentation of the resulting oxyanion into the carboxylic acid and a benzyl anion.
Tetrahydroquinazolines and dihydrocyclopentapyrimidines as CRF antagonists
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Page/Page column 12, (2010/02/10)
Compounds of the formula (I): and pharmaceutically acceptable salts or prodrugs thereof, wherein m, R1, R2, R3, R4, R5 and R6 are as defined herein. The invention also provides methods for
Mg-promoted mixed pinacol coupling
Maekawa, Hirofumi,Yamamoto, Yoshimasa,Shimada, Hisashi,Yonemura, Kazuaki,Nishiguchi, Ikuzo
, p. 3869 - 3872 (2007/10/03)
Mg-promoted reduction of a mixture of aromatic ketones (or imines) and aliphatic carbonyl compounds in N,N-dimethylformamide (DMF) brought about unique mixed pinacol type of cross coupling to give unsymmetrical vicinal diols (or amino alcohols) or α-hydroxyketones in good to moderate yields. The reaction may be initiated by electron transfer from magnesium metal to an aromatic carbonyl compound possessing a less negative reduction potential. The difference of reduction potential between aromatic ketones (or imines) and aliphatic carbonyl compounds was found to be one of the important key factors in this selective cross coupling.
Fluorotetraphenylbismuth: A new reagent for efficient regioselective α-phenylation of carbonyl compounds
Ooi, Takashi,Goto, Ryoji,Maruoka, Keiji
, p. 10494 - 10495 (2007/10/03)
Synthesis and X-ray crystallographic characterization of fluorotetraphenylbismuth (1) has been achieved for the first time, revealing that the bismuth center of 1 adopts a distorted trigonal bipyramidal geometry with three ipso carbons at the equatorial sites and one ipso carbon and fluorine atom at the apical sites. Contrary to the previous common understanding of this type of organobismuth(V) compound, 1 was found to be thermally stable, maintaining its amphiphilic property. Hence, 1 can be used as an off-the-shelf reagent in organic synthesis, and its utility has been clearly demonstrated in applications to the efficient α-phenylation of ketones and esters. For instance, simple mixing of 1 and 1-trimethylsiloxy-3,4-dihydronaphthalene in THF at -40 °C and stirring at room temperature for 10 min gave rise to 2-phenyl-1-tetralone almost quantitatively without formation of the polyphenylated products. In addition to the generality of this method, applicability of our approach to the selective α-alkenylation of carbonyl compounds was also demonstrated by the use of fluoro(2-phenylethenyl)tris(p-tolyl)bismuth (2) as a representative reagent. These results imply the vast potential of organobismuth(V) compounds of type 1 and 2 as useful precursors of a wide variety of pentavalent organobismuth compounds based on the utilization of the eminent fluorine-silicon interaction or the inherent basicity of the fluorine atom. Copyright
Direct and Regiocontrolled Synthesis of α-Phenyl Ketones from Silyl Enol Ethers and Diphenyliodonium Fluoride
Chen, Kuanchiang,Koser, Gerald F.
, p. 5764 - 5767 (2007/10/02)
The efficiacy of diphenyliodonium fluoride (1, DIF) for the phenylation of silyl enol ethers was investigated.When the silyl enol ethers of cyclopentanone, 2-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, acetophenone, 2-pentanone, diisopropyl ketone, and pinacolone were mixed with DIF in tetrahydrofuran, either α-phenyl or α,α-diphenyl ketones were produced and isolated in yields ranging from 20 to 88percent.That the regiochemistry of α-phenylation can be controlled by an appropriate choice of silyl enol ether was demonstrated with the kinetic and thermodynamic silyl enol ethers of 2-methylcyclohexanone, the thermodynamic silyl enol ether of 2-methylcyclopentanone, and the kinetic silyl enol ether of 2-pentanone. 3,3-Dimethyl-2-(silyloxy)-1-butene gave a dehydro dimer of pinacolone with DIF in addition to α-phenylpinacolone, thus suggesting that phenylations of silyl enol ethers with DIF may proceed via radical intermediates.
Intramolecular Nucleophilic Addition to Unsaturated Carbon. Dependence of Cyclization Efficiency on the Method of Carbon-Carbon Bond Cleavage Utilized To Generate the Reactive Species
Paquette, Leo A.,Gilday, John P.,Maynard, George D.
, p. 5044 - 5053 (2007/10/02)
The following three reactions have been studied for the purpose of comparing their intrinsic ability to generate carbanionic intermediates capable of intramolecular cyclization: (a) the Haller-Bauer cleavage of ketones 15a and 15b, as well as the (S)-(+)-antipode of 15a (viz. 47); (b) the base-promoted cleavage of 1,1-diarylcarbinols 16a and 16b; (c) decarboxylative elimination within the methyllithium adducts of carboxylic acids 17a and 17b.The Haller-Bauer process proceeds predominantly via carbanion intermediates, which most often experience protonation to give 18 an d 21.Cyclization becomes possible, however, under certain circumstances and reaches a maximum of 33percent with NaNH2 in benzene.Using (+)-47 as a probe, it has been possible to ascertain that 56percent of the reactive intermediate molecules racemize and that only the racemic species generates cyclic product.On the other hand, the Cram-type cleavages of 16a and 16b proceed mainly by homolytic cleavage to generate the benzophenone radical anion and free-radical intermediate.The latter dimerize, capture solvent, and abstract hydrogen to varying degrees depending upon counterion and solvent.Finally, reactions of type c are the most efficient at effecting intramolecular ring closure.
Ring Contraction of 2-Chlorocyclohexanone with Grignard Reagents
Hori, Mikio,Kataoka, Tadashi,Shimizu, Hiroshi,Imai, Eiji,Iwamura, Tatsunori,Maeda, Kaori
, p. 3599 - 3605 (2007/10/02)
The reaction of 2-chlorocyclohexanone with phenylmagnesium bromide in refluxing tetrahydrofuran unexpectedly afforded the ring-contracted product, cyclopentyl phenyl ketone, as the main product in moderate yield.The reactivities of several cyclic 2-haloketones were examined.Keywords - 2-chlorocyclohexanone; Grignard reaction; ring contraction; cyclopentyl phenyl ketone; solvent effect; THF; conformational isomer
