1590-08-5Relevant articles and documents
Amine-catalyzed decarboxylative aldol reaction of β-ketocarboxylic acids with trifluoropyruvates
Kawanishi, Ryouta,Hattori, Shinya,Iwasa, Seiji,Shibatomi, Kazutaka
, (2019)
Decarboxylative aldol reaction of aliphatic carboxylic acids is a useful method for C–C bond formation because carboxylic acids are an easily available class of compounds. In this study, we found that the decarboxylative aldol reaction of tertiary β-ketocarboxylic acids and trifluoropyruvates proceeded smoothly to yield the corresponding aldol products in high yields and with high diastereoselectivity in the presence of a tertiary amine catalyst. In this reaction, we efficiently constructed a quaternary carbon center and an adjacent trifluoromethylated carbon center. This protocol was also extended to an enantioselective reaction with a chiral amine catalyst, and the desired product was obtained with up to 73% enantioselectivity.
Probing the regioselective C-deuteriation of lithium enolates derived from 2-methyl-tetralone in the presence of substituted tertiary amines
Begum, Mothia,Chavda, Sameer,Coumbarides, Gregory S.,Dingan, Marco,Eames, Jason,Suggate, Michael J.,Weerasooriya, Neluka
, p. 707 - 732 (2006)
Results are reported on the regioselective C-deuteriation of 2-methyl-tetralone using a series of D-sources and tertiary amines as potential mediators. The results presented further aid the understanding of kinetic deuteriation of both 'base-containing' and 'base-free' enolates. Copyright
A chiral 1,4-oxazin-2-one: Asymmetric synthesis versus resolution, structure, conformation and VCD absolute configuration
Solladie-Cavallo,Sedy,Salisova,Biba,Welch,Nafie,Freedman
, p. 2703 - 2707 (2001)
1,4-Oxazin-2-one 3 is obtained from 2-pinanone in 4 steps and 78% overall yield. Enantiopure (e.e. >99%) (R)-(+)-3 and (S)-(-)-3 were obtained through chiral supercritical fluid chromatography (using a semi preparative Chiralpak AS column) with almost quantitative recovery of material. The structure and the boat-conformation of the lactone ring have been determined by NMR and the absolute configuration determined by VCD.
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Barry et al.
, p. 4737 (1971)
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The synthesis and characterization of 2-trideuteriomethyl and 2,2-di(trideuteriomethyl) aryl ketones
Coumbarides, Gregory S.,Eames, Jason,Weerasooriya, Neluka
, p. 935 - 942 (2002)
Results are reported on the synthesis and characterization of a variety of trideuteriomethyl aryl ketones. Copyright
Electron transfer promoted regioselective ring-opening reaction of cyclopropyl silyl ethers
Hasegawa, Eietsu,Yamaguchi, Naoto,Muraoka, Hiroyasu,Tsuchida, Hiroyuki
, p. 2811 - 2814 (2007)
Oxidative ring-opening reactions of cyclopropyl silyl ethers incorporated into bicyclo[m.1.0]alkane framework were investigated. The results show that the regioselectivities for ring-opening of intermediate radical cations, formed by single electron transfer, are governed by the nature of the nucleophile as well as oxidizing species.
Role of the Ring Methyl Groups in 2′,3′-Benzoabscisic Acid Analogues
Wan, Chuan,Hong, Qilin,Zhang, Xueqin,Zeng, Yuejuan,Yang, Dongyan,Che, Chuanliang,Ding, Shanshan,Xiao, Yumei,Li, Jia-Qi,Qin, Zhaohai
, (2019)
Five analogues of iso-PhABA (20) developed earlier by our research group were designed and synthesized. The bioassay results show that the number and position of methyl groups along with the substitution of hydrogen atoms of the methyl group have a great influence on the activity. Compared with iso-PhABA, the inhibitory activity of diMe-PhABA (21) on seed germination and rice seedling growth decreased slightly; however, it significantly reduced the capability of inhibiting wheat embryo germination. Both 3′-deMe-iso-PhABA (22) and 2′-deMe-PhABA (23) exhibited weak inhibitory activities, and 11′-methoxy iso-PhABA (24a/24b) was much more efficient than its isomer 24c/24d in all bioassays. These results reveal the preservation of quaternary carbon at the 2′ or 3′ position is necessary to maintain its ABA-like biological activity, and demethylation at the 3′ position has a more significant effect. The selectivity of these compounds to different physiological processes makes them available as selective probes for different ABA receptors.
(R)-(+)-[VCD(-)984]-4-Ethyl-4-methyloctane: A cryptochiral hydrocarbon with a quaternary chiral center. (1) synthesis of the enantiopure compound and unambiguous determination of absolute configuration
Fujita, Takuma,Obata, Kazuhiro,Kuwahara, Shunsuke,Nakahashi, Atsufumi,Monde, Kenji,Decatur, John,Harada, Nobuyuki
, p. 6372 - 6384 (2010)
Enantiopure (R)-(+)-[VCD(-)984]-4-ethyl-4-methyloctane (1), a cryptochiral hydrocarbon with a quaternary chiral center, was synthesized by the use of 2-methoxy-2-(1-naphthyl)propionate (Mα NP) and (-)-camphorsultam dichlorophthalic (CSDP) acid methods. The diastereomeric Mα NP and CSDP acid esters prepared from racemic 2-butyl-2-methyl-1-tetralols, were effectively separated by HPLC on silica gel, and their absolute configurations were unambiguously determined by X-ray crystallographic analysis and 1H NMR anisotropy methods. The recovered enantiopure 2-butyl-2-methyl-1-tetralol [(1S,2S)-(+)-cis-9] was then converted into the hydrocarbon (+)-1, the R absolute configuration of which was unambiguously determined for the first time. The structure of hydrocarbon 1 was also confirmed by NMR HSQC-TOCSY analysis. Copyright
Enantioselective protonation of a lithium enolate derived from 2-methyl-1-tetralone using chiral sulfonamides
Coumbarides, Gregory S.,Eames, Jason,Scheuermann, J. Erik W.,Sibbons, Kevin F.,Suggate, Michael J.,Watkinson, Michael
, p. 906 - 909 (2005)
The synthesis of enantiomerically enriched (R)-2-methyl-1-tetralone (1) with 77% e.e. was achieved through protonation of its lithium enolate (3) using a C2-symmetric tris-sulfonamide (6) as an internal chiral proton source. Access to the complementary (S)-enantiomer 1 with 33% e.e. was achieved using a related C2-symmetric bis-sulfonamide (9) as the chiral proton source.
Stereoselective protonation of 2-methyl-1-tetralone lithium enolate catalyzed by salan-type diamines
?owicki, Daniel,Watral, Justyna,Jelecki, Maciej,Bohusz, Wiktor,Kwit, Marcin
, (2021/04/02)
Asymmetric protonation of ketone enolates is a convenient alternative to asymmetric alkylation of enolates that allows to convert racemic ketones into their optically active form. Here, we have reported an efficient enantioselective protonation of 2-methyl-1-tetralone lithium enolate catalyzed by salan-type diamines. A broad series of salan-type catalysts were synthesized, including several previously unknown, and subsequently tested in the title reaction. For the first time, a chiral amine used as organocatalyst has shown better results than as stoichiometric protonating agent. Application of only 10 mol% of salan allows to obtain the title ketone with high yield and enantiomeric excess up to 75%. The DFT calculations of the structure of the catalyst and its complex with lithium enolate were conducted, which makes it possible to propose a likely reaction mechanism.
Preparation method of menadione sodium hydrogen sulfite
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Paragraph 0058; 0068-0071, (2021/07/31)
The invention provides a preparation method of menadione sodium hydrogen sulfite. The preparation method comprises the following steps of: by taking alpha-methyl-gamma-butyrolactone and benzene as raw materials, preparing 2-methyl-3, 4-dihydro-1 (2H)-naphthalenone through Friedel-Crafts reaction; carrying out halogenation reaction on the 2-methyl-3, 4-dihydro-1 (2H)-naphthalenone and a halogenation reagent at the ortho position of carbonyl, and carrying out alkali elimination to prepare 2-methyl-1-naphthol; oxidizing the 2-methyl-1-naphthol through air to obtain 2-methyl-1, 4-naphthoquinone; and carrying out addition reaction on the 2-methyl-1, 4-naphthoquinone and sodium hydrogen sulfite to prepare the menadione sodium hydrogen sulfite. According to the method, the raw materials are cheap, easily available and low in cost; the process operation is safe, simple and convenient, less process wastewater is generated, and the method is green and environment-friendly; and the stability of the raw materials and intermediate products is high, high reaction activity and selectivity are high, reaction conditions are easy to realize, side reactions are few, the purity and yield of the product are high, and industrial production of the menadione sodium bisulfite can be facilitated.
Extending the Substrate Scope in the Hydrogenation of Unfunctionalized Tetrasubstituted Olefins with Ir-P Stereogenic Aminophosphine-Oxazoline Catalysts
Biosca, Maria,Salomó, Ernest,De La Cruz-Sánchez, Pol,Riera, Antoni,Verdaguer, Xavier,Pàmies, Oscar,Diéguez, Montserrat
supporting information, p. 807 - 811 (2019/01/26)
Air-stable and readily available Ir-catalyst precursors modified with MaxPHOX-type ligands have been successfully applied in the challenging asymmetric hydrogenation of tetrasubstituted olefins under mild reaction conditions. Gratifyingly, these catalyst precursors are able to efficiently hydrogenate not only a range of indene derivatives (ee's up to 96%) but also 1,2-dihydronapthalene derivatives and acyclic olefins (ee's up to 99%), which both constitute the most challenging substrates for this transformation.
