759-24-0Relevant articles and documents
Tautomerism in bis(oxazoline)s
Walli, Adam,Dechert, Sebastian,Meyer, Franc
, p. 7044 - 7049 (2013)
Bis(oxazoline)s (BOXs) are a privileged ligand class and have found widespread use in catalysis. Herein, the tautomerism of selected BOX ligands was evidenced by X-ray diffractometry as well as by NMR and IR spectroscopy and supported by DFT calculations. In CDCl3 solution at room temperature, the new 1,1-bis(4,4-dimethyl-1,3-oxazolin-2-yl)-1-phenylmethane ( Ph,HBOX-Me2) ligand is present as a 1:1 mixture of the diimine and iminoenamine tautomers. Thermodynamic and kinetic data for the tautomeric equilibrium were determined, which allowed comparison with related bidentate ligand classes. The other BOXs studied, H,HBOX-Me 2, Me,HBOX-Me2, and tBu,HBOX-Me 2, are largely present in the diimine form under similar conditions. IR spectroscopy was identified as a valuable tool for detecting the presence of the iminoenamine form as a minor component. Tautomerism in the prominent bis(oxazoline) ligand class is evidenced by X-ray diffractometry as well as by NMR and IR spectroscopy and supported by DFT calculations. Thermodynamic and kinetic data for the tautomeric equilibrium are determined for a specific example, which allows comparison with related bidentate ligand classes. Copyright
Enantioselective Desymmetrization of 2-Aryl-1,3-propanediols by Direct O-Alkylation with a Rationally Designed Chiral Hemiboronic Acid Catalyst That Mitigates Substrate Conformational Poisoning
Estrada, Carl D.,Ang, Hwee Ting,Vetter, Kim-Marie,Ponich, Ashley A.,Hall, Dennis G.
supporting information, (2021/04/07)
Enantioselective desymmetrization by direct monofunctionalization of prochiral diols is a powerful strategy to prepare valuable synthetic intermediates in high optical purity. Boron acids can activate diols toward nucleophilic additions; however, the design of stable chiral catalysts remains a challenge and highlights the need to identify new chemotypes for this purpose. Herein, the discovery and optimization of a bench-stable chiral 9-hydroxy-9,10-boroxarophenanthrene catalyst is described and applied in the highly enantioselective desymmetrization of 2-aryl-1,3-diols using benzylic electrophiles under operationally simple, ambient conditions. Nucleophilic activation and discrimination of the enantiotopic hydroxy groups on the diol substrate occurs via a defined chairlike six-membered anionic complex with the hemiboronic heterocycle. The optimal binaphthyl-based catalyst 1g features a large aryloxytrityl group to effectively shield one of the two prochiral hydroxy groups on the diol complex, whereas a strategically placed "methyl blocker"on the boroxarophenanthrene unit mitigates the deleterious effect of a competing conformation of the complexed diol that compromised the overall efficiency of the desymmetrization process. This methodology affords monoalkylated products in enantiomeric ratios equal or over 95:5 for a wide range of 1,3-propanediols with various 2-aryl/heteroaryl groups.
A amide alkaloid fully synthetic method
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Paragraph 0056; 0057, (2017/08/25)
The invention discloses a total synthesis method of amides alkaloid, and belongs to the technical field of the chemistry of natural products. The total synthesis method comprises the following steps: carrying out the synthesis by adopting malonate and 2-bromopropane or 2-bromopropane derivative as raw materials, thereby obtaining isopropyl malonate; (2) carrying out the synthesis by adopting 2-aminopyrrolidine as a raw material, thereby obtaining mid-body 2-amino tetralin pyrrolidine; and (3) synthesizing amides alkaloid 3-isopropyl-nafoxidine[1,2-alpha]pyrimidine-2,4(1H,3H)-diketone and a derivative by adopting the isopropyl malonate and the 2-2-amino tetralin pyrrolidine as a raw material. By adopting the total synthesis method, the defect that the extraction separation process in the natural product is complicated and the yield is low can be overcome, and the demand of perople for further researching the natural product can be satisfied; moreover, the synthesis method is simple in route, raw materials are cheap and easy to obtain, and the yield is relatively high.
Synthesis and acidity of conformationally constrained 1,3-oxathiane S-oxides
Weingand, Daniel,Podlech, Joachim
, p. 5608 - 5610 (2016/11/28)
Conformationally constrained 5-tert-butyl 1,3-oxathiane was synthesized and oxidation led to the diastereoisomeric sulfoxides and the respective sulfone. Stereoelectronic effects are discussed for these compounds and their corresponding 2-carbanions. pKavalues are calculated for these compounds and compared with the respective 1,3-dithiane-derived sulfide, the sulfoxides, and the sulfone.
METHOD OF PRODUCING 3-ETHOXY-2-TERT-BUTYL ALKYL PROPIONATE
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Paragraph 0039; 0040, (2016/12/22)
PROBLEM TO BE SOLVED: To provide a novel production method of 3-ethoxy-2-tert-butyl alkyl propionate used for the production of an olefin polymerization solid catalyst. SOLUTION: A 2-ethoxy methyl malonic acid diester derivative represented by formula (1) (where R1 and R2 represent a 1-4C alkyl group) is reacted in the presence of a base. COPYRIGHT: (C)2015,JPO&INPIT
Selective sulfenylative desulfonylation or decarbalkoxylation of α-sulfonyl malonates with DABCO or Bu3N: Reactivity and conformational analysis
Donnici, Claudio L.,Pereira, Elaine Henriques Teixeira,Lopes, Julio C. Dias,Marzorati, Liliana,Wladislaw, Blanka
scheme or table, p. 342 - 350 (2010/04/04)
The study on reactivity of severalαsubstituted αsulfonyl malonates toward 1,4-diazabicyclo[2.2.2]octane (DABCO) and Bu3N is described. The reactivity with DABCO revealed the possible competition between decarbalkoxylation and unexpected desulfonylation, depending on the-substituent, because of sterical hindrance around the electrophilic centers (SO2 and CO2R). The derivatives with crowded α-substituents suffer selective desulfonylation, and a novel and efficient desulfonylation method can be proposed. The dependence of the reactivity ofα-sulfonyl malonates on the sterical hindrance around the electrophilic centers is confirmed by conformational analysis (Macromodel/MM2* and Mopac/MP3). The carbanionic mechanism is proved because the corresponding protonated, deuterated, and sulfenylated products were obtained by addition of the corresponding electrophilic agents. Bu3N showed itself to be a novel selective decarbalkoxylation agent for any-substituted-sulfonyl malonate.
ORGANOMANGANESE (II) REAGENTS XV. CONJUGATE ADDITION OF ORGANOMANGANESE REAGENTS TO ALKYLIDENEMALONIC ESTERS AND RELATED COMPOUNDS
Cahiez, Gerard,Alami, Mouad
, p. 4163 - 4176 (2007/10/02)
Organomanganese reagents react with alkylidenemalonic esters or related compounds to give the conjugate addition products in good yields.Several examples illustrate the scope and the efficiency of this reaction.
ANALYSE STRUCTURALE EN SERIE CYCLOBUTANIQUE. Partie 1. Derives monosubstitues et gem disubstitues du cyclobutane
Karimine, Mohamed,Galsomias, Jacqueline,Lere-Porte, Jean-Pierre,Petrissans, Jean
, p. 321 - 332 (2007/10/02)
Methylene bending mode analysis of some cyclobutane-d2 molecules reveals that in the dissolved state (solvent CCl4), bromocyclobutane occurs exclusively in a pseudo-equatorial form, whereas, under the same conditions, cyclobutanol and 1-bromocyclobutane carbonitrile exist both in pseudo-axial and pseudo-equatorial conformations.NMR spectroscopy confirms the results obtained for bromocyclobutane and leads to the conclusion that the pseudo-equatorial conformer is predominant in the case of cyclobutanol as well as in that of cyclobutane carbonitrile.A theoretical study of cyclobutanol in the gaseous state by the P.C.I.L.O. method gives results which are consistent with a pseudo-equatorial conformer.
Synthesis of 4-Ylidenebutenolides. A Practical Route to 2-En-4-ynoic Acid Intermediates based on Conjugate Addition of Alkynyl-lithium Reagents
Clemo, Nicholas G.,Pattenden, Gerald
, p. 2133 - 2136 (2007/10/02)
Conjugate addition of alkynyl-lithium reagents to diethyl ethoxymethylenemalonate, followed by simultaneous saponification and 1,2-elimination of ethanol from the intermediate adducts, viz (18), in the presence of ethanolic potassium hydroxide, provides a useful synthesis of substituted propargylidenemalonic acids (19).Cyclisation of the propargylidenemalonic acids, using known procedures then leads to the corresponding 4-ylidenebutenolides, e.g. (20) and (21)
Chemistry of Cumulenes, 6. Syntheses and Reactions of 1-H-Allene-1,3-dicarboxylic Acid Monoesters
Nader, Franz W.,Brecht, Angelika,Kreisz, Siegfried
, p. 1196 - 1207 (2007/10/02)
The title compounds 5a-e have been prepared.The carboxylation of allene monoesters 4 was successful with the phenyl derivative 4a only.The resulting extremely unstable halfester 5a as its benzylammonium salt was spontaneously transformed into the enamine ester 7.The alkyl-substituted allenes 5b-e are accessible via Wittig reaction of alkylmalonic monoester chlorides 11 with (alkoxycarbonyl)methylene ylides 12, which comprise the 2,2,2-trichloroethyl or the tert-butyl residues as selectively cleavable carboxylic protecting groups.Cleavage of the CCl3CH2 group with Zn succeeded for the tert-butylallenes 13a/b only.In the case of the methylallene 13c the cleavage was accompanied by hydrogenation of the allene.The mechanism of this reaction is discussed.Cleavage of the tert-butyl ester group in 13d and e was readily achieved with ether/sulfuric acid.
