1120-72-5Relevant articles and documents
Optical Rotatory Dispersion Studies. 134. Absolute Configuration and Circular Dichroism Spectrum of (R)-Cyclopentanone. Demonstration of a Conformational Isotope Effect
Sundararaman, P.,Barth, Guenter,Djerassi, Carl
, p. 5004 - 5007 (1981)
The absolute configuration of (R)-cyclopentanone is established through synthesis using as the key step chiral epoxidation with the Sharpless reagent.Its circular dichroism (CD) spectrum is unusual in that it exhibits a bisignate Cotton effect being negative at 310 and positive at 275 nm.From the interpretation on the variable-temperature CD measurements, the unexpected conclusion is reached that the twist conformation with the deuterium in the quasi-equatorial position is energetically preferred by ca. 10 +/- 2 cal/mol.Evidently, even at room temperature, the contribution toward the spectrum resulting from the conformational isotope effect is of the same or larger amplitude but opposite sign compared to the difference between the partial octant contributions of an α-quasi-equatorial and α-quasi-axial deuterium substituent.
A novel ene-reductase from Synechococcus sp. PCC 7942 for the asymmetric reduction of alkenes
Fu, Yilei,Hoelsch, Kathrin,Weuster-Botz, Dirk
, p. 1988 - 1997 (2012)
The increasing demand for enantiopure molecules in the pharmaceutical and fine-chemical industry requires the availability of well-characterized and efficient biocatalysts for asymmetric syntheses. Thereby, asymmetric reduction of alkenes represents one of the most employed reactions for the production of chiral molecules. Here, we present a novel ene-reductase from the cyanobacterium Synechococcus sp. PCC 7942, a member of the old yellow enzyme family, capable of reducing CC bonds in a anti-specific fashion. We evaluated its biocatalytic potential by characterizing the substrate spectrum, cofactor preference, stereoselectivity and biochemical properties. This NADPH-dependent flavoprotein accepted a wide range of activated alkenes and displayed a pH optimum between pH 7.6 and pH 8.6. A C-terminal His6-tag decreased the enzyme activity 2.7-fold, but did not influence the stereoselectivity. The reduction of (R)-carvone and 2-methylmaleimide yielded (R)-products with high optical purities (98% de and >99% ee, respectively), pointing out the applicability of this new biocatalyst in the stereoselective production of chiral compounds.
Synthesis of cycloalkanones from dienes and allylamines through C-H and C-C bond activation catalyzed by a rhodium(I) complex
Lee, Dae-Yon,Kim, In-Jung,Jun, Chul-Ho
, p. 3031 - 3033 (2002)
Formaldehyde in disguise: The allylic amine 1 is used as a masked form of formaldehyde in the rhodium-catalyzed cyclization of dienes 2. The reaction provides access to various cycloalkanones 3 through chelation-assisted C-H- and C-C-bond activation.
ATTEMPTED GENERATION OF HALOCARBENES: PROTODESILYLATION OF DIHALOMETHYLSILANES
Larson, Gerald L.,Cadiz, Carlos
, p. 113 - 116 (1982)
Attempts to generate chlorocarbene or bromocarbene from (dichloromethyl)trimethylsilane and (dibromomethyl)trimethylsilane, respectively, under phase transfer conditions results in protodesilylation.The protodesilylation of 1,1-dihalosilanes under phase transfer conditions appears to be general.Phase transfer conditions are also useful for the protodesilylation of other organosilanes.
The alkylation of silyl enol ethers with SN1-unreactive iodides in the presence of silver trifluoroacetate
Jefford, Charles W.,Sledeski, Adam W.,Lelandais, Patrick,Boukouvalas, John
, p. 1855 - 1858 (1992)
Silyl enol ethers can be effectively alkylated with primary n-alkyl iodides in the presence of silver trifluoro-acetate to give monoalkyl ketones.
Studies on the chemistry of diols and cyclic ethers-53. Dehydration of 1,1-bishydroxymethylcycloalkanes: A quest for a 1,3-hydride shift
Molnar, Arpad,Bucsi, Imre,Bartok, Mihaly
, p. 4929 - 4936 (1992)
A study of the sulphuric acid-catalysed dehydrations of 1,1-bishydroxymethyl-cyclopropane, - cyclobutane, - cyclopentane and -cyclohexane (1a-1d) revealed that the product distributions are determined by the relative stabilities of carbenium ions and der kinetic control furnished evidence of a 1,3-hydride shift.
Conversion of furfural into cyclopentanone over Ni-Cu bimetallic catalysts
Yang, Yanliang,Du, Zhongtian,Huang, Yizheng,Lu, Fang,Wang, Feng,Gao, Jin,Xu, Jie
, p. 1932 - 1940 (2013)
The conversion of furfural into cyclopentanone over Ni-Cu bimetallic catalysts was studied under hydrogen atmosphere. Furfuryl alcohol, 4-hydroxy-2-cyclopentenone and 2-cyclopentenone were verified as three key intermediates. Rearrangement of the furan ring was independent of hydrogenation, starting from furfuryl alcohol rather than furfural. The opening and closure of the furan ring were closely related to the attack of a H2O molecule on the 5-position of furfuryl alcohol. Prior hydrogenation of the aldehyde group accounted for the different reactivity of furfural and furfuryl alcohol. The high selectivity of cyclopentanone was ascribed to the presence of 2-cyclopentenone.
Effects of HMPA on the Structure and Reactivity of the Lithium Enolate of Cyclopentanone in THF: The Dimer is Responsible for Alkylation and Proton Exchange Reactions
Suzuki, Masaaki,Koyama, Hiroko,Noyori, Ryoji
, p. 259 - 268 (2004)
The structure and reactivity of the lithium enolate of cyclopentanone are strongly influenced by coexisting HMPA molecules. Detailed low-temperature 7Li, 31P, and 13C NMR studies of the 0.04-0.2 M THF solutions indicate that excess quantities of HMPA act primarily to form a bis-HMPA coordinated dimer. Tetrameric, trimeric, and monomeric enolates were not detected by HMPA titration. The convergency on the dimeric aggregate has been monitored by the successive displacement of THF with HMPA molecules. Even at a high concentration of HMPA, the formation of monomeric enolate was not observed. Kinetic experiments, combined with the structural information, showed that alkylation of the enolate by methyl iodide proceeds via the dimer with the assistance of HMPA. Proton exchange between the enolate and 2-methylcyclopentanone also occurs via the dimer, but without the participation of additional HMPA. These findings explain the role of HMPA in the selective monoalkylation of lithium enolate.
Efficient and selective hydrogenation of biomass-derived furfural to cyclopentanone using Ru catalysts
Fang, Ruiqi,Liu, Hongli,Luque, Rafael,Li, Yingwei
, p. 4183 - 4188 (2015)
The selective hydrogenation of furfural into cyclopentanone is an attractive transformation to advance in the sustainable synthesis of important chemicals from biomass. A supported Ru nanoparticle catalyst on an acidic MOF material (Ru/MIL-101) was designed for the highly active and selective conversion of furfural to cyclopentanone in aqueous media. Complete conversion of furfural with a selectivity higher than 96% was achieved within 2.5 h at 160 °C and 4.0 MPa H2 pressure.
Asymmetric intramolecular C-H/Olefin coupling: Asymmetric cyclization reactions of 1,5-dienes catalyzed by rhodium complexes
Fujii, Naoaki,Kakiuchi, Fumitoshi,Yamada, Airi,Chatani, Naoto,Murai, Shinji
, p. 425 - 426 (1997)
Asymmetric intramolecular C-H/olefin coupling reactions of 1-(2-pyridyl)- or 1-(1-methyl-2-imidazolyl)-1,5-dienes are catalyzed by a rhodium complex having a homochiral monodentate phosphine ligand.
