36099-26-0Relevant articles and documents
Selective N1/N4 1,4-Cycloaddition of 1,2,4,5-Tetrazines Enabled by Solvent Hydrogen Bonding
Zhu, Zixi,Glinkerman, Christopher M.,Boger, Dale L.
supporting information, p. 20778 - 20787 (2020/12/22)
An unprecedented 1,4-cycloaddition (vs 3,6-cycloaddition) of 1,2,4,5-tetrazines is described with preformed or in situ generated aryl-conjugated enamines promoted by the solvent hydrogen bonding of hexafluoroisopropanol (HFIP) that is conducted under mild reaction conditions (0.1 M HFIP, 25 °C, 12 h). The reaction constitutes a formal [4 + 2] cycloaddition across the two nitrogen atoms (N1/N4) of the 1,2,4,5-tetrazine followed by a formal retro [4 + 2] cycloaddition loss of a nitrile and aromatization to generate a 1,2,4-triazine derivative. The factors that impact the remarkable change in the reaction mode, optimization of reaction parameters, the scope and simplification of its implementation through in situ enamine generation from aldehydes and ketones, the reaction scope for 3,6-bis(thiomethyl)-1,2,4,5-tetrazine, a survey of participating 1,2,4,5-tetrazines, and key mechanistic insights into this reaction are detailed. Given its simplicity and breath, the study establishes a novel method for the simple and efficient one-step synthesis of 1,2,4-triazines under mild conditions from readily accessible starting materials. Whereas alternative protic solvents (e.g., MeOH vs HFIP) provide products of the conventional 3,6-cycoladdition, the enhanced hydrogen bonding capability of HFIP uniquely results in promotion of the unprecedented formal 1,4-cycloaddition. As such, the studies represent an example of not just an enhancement in the rate or efficiency of a heterocyclic azadiene cycloaddition by hydrogen bonding catalysis but also the first to alter the mode (N1/N4 vs C3/C6) of cycloaddition.
Nucleophilic Organic Base DABCO-Mediated Chemospecific Meinwald Rearrangement of Terminal Epoxides into Methyl Ketones
Li, Siqi,Shi, Yi,Li, Pingfan,Xu, Jiaxi
, p. 4443 - 4450 (2019/04/30)
Nucleophilic organic base DABCO (1,4-diazabicyclo[2.2.2]octane)-mediated Meinwald rearrangement of various epoxides was investigated. 2-Aryl-, alkenyl-, and alkynylepoxides generate the corresponding methyl ketones chemospecifically in good to excellent yields. The current DABCO-mediated Meinwald rearrangement of epoxides features readily accessible starting materials, a wide substrate scope, a transition-metal- and acid-free environment, and chemospecificity in the isomerization of epoxides.
Selective Asymmetric Transfer Hydrogenation of α-Substituted Acetophenones with Bifunctional Oxo-Tethered Ruthenium(II) Catalysts
Yuki, Yamato,Touge, Taichiro,Nara, Hideki,Matsumura, Kazuhiko,Fujiwhara, Mitsuhiko,Kayaki, Yoshihito,Ikariya, Takao
, p. 568 - 574 (2017/12/13)
A practical method for the asymmetric transfer hydrogenation of α-substituted ketones was developed utilizing oxo-tethered N-sulfonyldiamine-ruthenium complexes. Reduction by HCO2H and HCO2K in a mixed solvent of EtOAc/H2O allowed for the selective synthesis of halohydrins from 2-bromoacetophenone (98%) and 2-chloroacetophenone (>99%), leading to suppressed undesired side reactions stemming from formylation under the typical reaction conditions using an azeotropic 5:2 mixture of HCO2H and Et3N. A range of functional groups, such as halogens, methoxy, nitro, dimethylamino, and ester groups, were well tolerated, highlighting the potential of this method. Nearly complete selectivity with a preferable ee was maintained even with a substrate/catalyst (S/C) ratio of 5000. This catalyst system was also effective for the asymmetric reduction of α-sulfonated ketones without eroding the leaving group. (Figure presented.).
Regioselective hydrosilylation of epoxides catalysed by nickel(II) hydrido complexes
Wenz, Jan,Wadepohl, Hubert,Gade, Lutz H.
supporting information, p. 4308 - 4311 (2017/04/21)
Bench-stable nickel fluoride complexes bearing NNN pincer ligands have been employed as precursors for the regioselective hydrosilylation of epoxides at room temperature. A nickel hydride assisted epoxide opening is followed by the cleavage of the newly formed nickel oxygen bond by σ-bond metathesis with a silane.
Halohydrin and its derivatives low priced high-efficient synthetic method (by machine translation)
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Paragraph 0188; 0189; 0190; 0191, (2017/08/25)
The invention discloses a halohydrin low priced high-efficient synthetic method, the organic solvent of formula I shown in the olefin compound with a halide, sulfoxide and additive mixing, by the olefin of hydroxy halogenate reaction, can be a high selectivity of the halohydrin the system results in the type II shown, wherein R1 , R2 , R3 , R4 , R5 And R6 Are selected from hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, ester, acyl, amido, dialkyl amino, aryl, substituted aromatic, heterocyclic aromatic group or substituted heterocyclic aromatic, R1 , R2 , R3 , R4 , R5 And R6 The presence of the respective independent may be identical or different; or R1 And R2 , R1 And R3 , R2 And R4 , R3 And R4 , R5 And R6 Combining to form a cycloalkyl or substituted cycloalkyl, benzo ring alkyl or substituted cycloalkyl, heterocycle or substituted heterocycle; M selected from hydrogen, lithium, sodium, potassium, cesium, beryllium, magnesium, calcium, strontium, barium, zinc, copper, iron, ammonium or tetraalkyl ammonium; X chlorine, bromine or iodine. (by machine translation)
Catalytic Enantioselective Conversion of Epoxides to Thiiranes
Liao, Saihu,Leutzsch, Markus,Monaco, Mattia Riccardo,List, Benjamin
supporting information, p. 5230 - 5233 (2016/05/19)
A highly efficient and enantioselective Br?nsted acid catalyzed conversion of epoxides to thiiranes has been developed. The reaction proceeds in a kinetic resolution, furnishing both epoxide and thiirane in high yields and enantiomeric purity. Heterodimer formation between the catalyst and sulfur donor affords an effective way to prevent catalyst decomposition and enables catalyst loadings as low as 0.01 mol %.
From simple organobromides or olefins to highly value-added bromohydrins: A versatile performance of dimethyl sulfoxide
Song, Song,Huang, Xiaoqiang,Liang, Yu-Feng,Tang, Conghui,Li, Xinwei,Jiao, Ning
, p. 2727 - 2731 (2015/05/27)
A novel and efficient direct transformation of secondary bromides or olefins to highly value-added bromohydrins has been disclosed. Dimethyl sulfoxide (DMSO), a cheap and common solvent, performs its versatile role as a solvent, an essential oxidant, and also as an oxygen source in this bromohydrin synthesis.
Practical iron-catalyzed hydrogen peroxide epoxidation of aromatic olefins using a combination of two kinds of simple picolinate ligands under halide-free reaction conditions
Chishiro, Takefumi,Kon, Yoshihiro,Nakashima, Takuya,Goto, Midori,Sato, Kazuhiko
supporting information, p. 623 - 627 (2014/05/20)
High-yield syntheses of epoxides using an iron complex having two types of picolinates in the presence of hydrogen peroxide under halide-free reaction conditions were achieved. The reaction is very simple. The complex, prepared with iron(II) acetate, 2-pi
Nickel-catalyzed cross-coupling of styrenyl epoxides with boronic acids
Nielsen, Daniel K.,Doyle, Abigail G.
supporting information; experimental part, p. 6056 - 6059 (2011/09/13)
Let's get multicatalytic! A Ni0 catalyst complexed with a biaryldialkyl monophosphine ligand facilitates C-C bond formation between styrenyl epoxides and aryl boronic acids (see scheme). X-ray analysis of a catalytically active nickel/ligand complex supports a redox pathway involving C sp 3-O bond activation. A variety of α-substituted alcohols were generated with good reaction efficiency by a multicatalytic sequence. Copyright
2,5-DIOXOIMIDAZOLIDIN-4-YL ACETAMIDES AND ANALOGUES AS INHIBITORS OF METALLOPROTEINASE MMP12.
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Page 62, (2010/02/06)
The invention provides compounds of formula (I) in which L, X, Y, Z1, Z2, R1, R2, R3 and G2 have the meanings defined in the specification; processes for their preparation; pharmaceutical c
