495-45-4Relevant academic research and scientific papers
Novel synthesis of oxadiazinone and oxadiazepinone derivatives by ring expansion of diaziridinone
Komatsu, Mitsuo,Sakai, Norio,Hakotani, Akira,Minakata, Satoshi,Ohshiro, Yoshiki
, p. 541 - 544 (2000)
Treatment of N, N'-di-tert-butyldiaziridinone with α-hydroxy ketones in the presence of a catalytic amount of BF3·OEt2 gave carbazate derivatives in excellent yields. Acid-catalyzed recyclization of these compounds easily proceeded to give oxadiazinone derivatives. The reaction was applicable to the synthesis of oxadiazepinone derivatives and also to one-pot process.
Rearrangement of dypnones to 1,3,5-triarylbenzenes
Deng, Kai,Huai, Qi-Yong,Shen, Zhi-Lun,Li, Hui-Jing,Liu, Chen,Wu, Yan-Chao
, p. 1473 - 1476 (2015)
Rearrangement of dypnones to 1,3,5-triarylbenzenes is described. The reaction is proposed to involve an aldol-type self-condensation of dypnones, followed by an intramolecular [2 + 2] cycloaddition and a retro-[2 + 2] cycloaddition. The reaction goes smoothly under obviously milder conditions in comparison to the cyclotrimerization of acetophenones to 1,3,5-triarylbenzenes (10 mol % of TsOH, 80 °C versus 130-148 °C). This unexpected rearrangement would provide new possible considerations in dypnone-involved organic synthesis.
Chemoselective reduction of ?,¢-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
, p. 590 - 599 (2021/03/29)
The selective reduction of ?,¢-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ¢ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ¢-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
Highly Enantioselective Iridium-Catalyzed Hydrogenation of Conjugated Trisubstituted Enones
Peters, Bram B. C.,Jongcharoenkamol, Jira,Krajangsri, Suppachai,Andersson, Pher G.
, p. 242 - 246 (2021/01/13)
Asymmetric hydrogenation of conjugated enones is one of the most efficient and straightforward methods to prepare optically active ketones. In this study, chiral bidentate Ir-N,P complexes were utilized to access these scaffolds for ketones bearing the stereogenic center at both the α- and β-positions. Excellent enantiomeric excesses, of up to 99%, were obtained, accompanied with good to high isolated yields. Challenging dialkyl substituted substrates, which are difficult to hydrogenate with satisfactory chiral induction, were hydrogenated in a highly enantioselective fashion.
HIGHLY ENANTIOSELECTIVE ACCESS TO CYCLIC BETA-AMINO ACIDS
-
Paragraph 0117; 0118, (2021/06/11)
Disclosed herein is a method of forming a compound of formula I: wherein the substituents are defined in the specification. In particular, the compounds of formula I can be converted to amino acids bearing quaternary stereocenters with exceptional optical purities.
Cobalt-Catalyzed Asymmetric 1,4-Hydroboration of Enones with HBpin
Ren, Xiang,Lu, Zhan
, p. 8370 - 8374 (2021/11/01)
Herein, a series of new 8-OIQ cobalt complexes were synthesized and used for cobalt-catalyzed chemo- and enantioselective 1,4-hydroboration of enones with HBpin to access chiral β,β-disubstituted ketones with good to excellent chemo- and enantioselectivties. This protocol is operationally simple and shows a broad substrate scope.
Preparation method of 1, 3-diphenyl-2-butene-1-ketone O-n-butyl oxime
-
Paragraph 0022-0024, (2021/06/23)
The invention relates to a preparation method of 1, 3-diphenyl-2-butene-1-ketone O-n-butyl oxime, and belongs to the technical field of organic synthesis. The method comprises the steps of by taking acetophenone as an initial raw material, dropwise adding thionyl chloride, carrying out solvent-free reaction under the catalysis of thionyl chloride, quenching, washing, extracting, and carrying out reduced pressure distillation to obtain purified 1, 3-diphenyl-2-butene-1-ketone; and sequentially adding hydroxylamine hydrochloride, potassium hydroxide, n-butyl bromide, ethanol and water into the obtained 1, 3-diphenyl-2-butene-1-ketone crude product, reacting at room temperature, and desolventizing the obtained product under reduced pressure to obtain the 1, 3-diphenyl-2-butene-1-ketone O-n-butyl oxime. By adopting the method disclosed by the invention, the 1, 3-diphenyl-2-butene-1-ketone O-n-butyl oxime can be prepared under conventional conditions, the intermediate does not need to be separated and purified, the operation is safe and simple, and the energy is saved. The method has the advantages of cheap initial raw materials and reduction of the production cost. The method is simple in process, low in energy consumption, convenient to operate and suitable for industrial large-scale production.
Visible Light Mediated Photocatalytic N-Radical Cascade Reactivity of O,δ-Unsaturated N-Arylsulfonylhydrazones: A General Approach to Structurally Diverse Tetrahydropyridazines
Azzi, Emanuele,Ghigo, Giovanni,Parisotto, Stefano,Pellegrino, Francesco,Priola, Emanuele,Renzi, Polyssena,Deagostino, Annamaria
, p. 3300 - 3323 (2021/02/16)
Tetrahydropyridazines are of particular interest for their versatility as intermediates in organic synthesis and display pharmacological activity in several domains. Here, we describe the photocatalytic synthesis of different tetrahydropyridazines starting from O,δ-unsaturated N-arylsulfonylhydrazones. Simple structural changes of substrates result into three different pathways beginning from a common N-hydrazonyl radical, which evolves through a domino carboamination/dearomatization, a HAT process, or a photoinduced radical Smiles rearrangement to afford diverse tetrahydropyridazines. All reactions are carried out in very mild conditions, and the quite inexpensive [Ru(bpy)3]Cl2 is used as the catalyst. Preliminary mechanism studies are presented, among them luminescence and electrochemical characterization of the involved species. Computational studies allow to rationalize the mechanism in accord with the experimental findings.
A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
supporting information, p. 16865 - 16873 (2021/10/20)
Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
Asymmetric Alkoxy- and Hydroxy-Carbonylations of Functionalized Alkenes Assisted by β-Carbonyl Groups
Dong, Kaiwu,Ji, Xiaolei,Ren, Xinyi,Shen, Chaoren,Tang, Lin,Tian, Xinxin,Wang, Zhen
, p. 17693 - 17700 (2021/07/10)
As a fundamental type of carbonylation reaction, the alkoxy- and hydroxy-carbonylation of unsaturated hydrocarbons constitutes one of the most important industrial applications of homogeneous catalysis. However, owing to the difficulties in controlling multi-selectivities for asymmetric hydrocarbonylation of alkenes, this reaction is typically limited to vinylarenes and analogues. In this work, a highly efficient asymmetric alkoxy- and hydroxy-carbonylation of β-carbonyl functionalized alkenes was developed, providing practical and easy access to various densely functionalized chiral molecules with high optical purity from broadly available alkenes, CO, and nucleophiles (>90 examples, 84–99 % ee). This protocol features mild reaction conditions and a broad substrate scope, and the products can be readily transformed into a diverse array of chiral heterocycles. Control experiments revealed the key role of the β-carbonyl group in determining the enantioselectivity and promoting the activity, which facilitates chiral induction by coordination to the transition metal as rationalized by DFT calculations. The strategy of utilizing an innate functional group as the directing group on the alkene substrate might find further applications in catalytic asymmetric hydrocarbonylation reactions.
