2044-08-8Relevant academic research and scientific papers
Complex-Base-Promoted Syn Eliminations from trans-1-Bromo-2-chlorocyclohexane
Croft, Alan P.,Bartsch, Richard A.
, p. 876 - 879 (1983)
Syn eliminations from trans-1-bromo-2-chlorocyclohexane (1) induced by complex-base combinations of NaNH2-NaOR(Ar) in tetrahydrofuran at room temperature favor dehydrochlorination (54-65percent) over dehydrobromination.Under the heterogeneous reaction conditions, oxyanion bases derived from tertiary, secondary, and branched primary alcohols as well as phenols and 2-butanone are effective complex-base components, which suggests that NaNH2 is the effective base species.Reactions of 1 with NaNH2-Na-t-Bu are not influenced by ultrasonic irradiation, but the propensity for lossof the normally poorer leaving group disappears in the presence of 15-crown-5.Transition states for complex-base-promoted syn eliminations are discussed.
Copper-Catalyzed C?P Cross-Coupling of (Cyclo)alkenyl/Aryl Bromides and Secondary Phosphine Oxides with in situ Halogen Exchange
Stankevi?, Marek,Wo?nicki, Pawe?
supporting information, p. 3484 - 3491 (2021/07/22)
An efficient protocol for concurrent tandem halogen exchange/C?P cross-coupling of cycloalkenyl bromides and secondary phosphine oxides has been developed. The catalytic system is based on cheap and air-stable copper(I) iodide as the precatalyst, commercially available N,N’-dimethylethylenediamine as the ligand, and Cs2CO3 or K2CO3 as the base. The use of sodium iodide as an additive reduces the excessive use of organic bromides to near-stoichiometric by promoting the in situ transformation to the corresponding iodides. Diarylphosphine oxides undergo cycloalkenylation with 35–99 % yields and dicyclohexylphosphine oxide with 30–53 % yields. In the case of acyclic alkenyl bromides the cross-coupling products undergo conjugate addition of diphenylphosphine oxide and satisfying yields are observed only for internal olefins. In the case of aryl bromides satisfying yields (43–72 %) are observed only for sterically unhindered arenes or arenes possessing an ortho-directing group. Cycloalkenylphosphine oxides prepared in the cross-coupling reaction undergo base-catalyzed and base-promoted conjugate addition to give bis(phosphinoyl)cycloalkanes.
One-Shot Radical Cross Coupling Between Benzyl Alcohols and Alkenyl Halides Using Ni/Ti/Mn System
Suga, Takuya,Takahashi, Yuuki,Ukaji, Yutaka
supporting information, p. 5622 - 5626 (2020/10/22)
A “one-shot” cross coupling between benzyl alcohols and alkenyl halides has been established. A combination of low-valent Ti-mediated C?OH homolysis and the prominent chemistry of Ni-based radical catalysis afforded the desired cross-coupled product with good efficiency. The reaction proceeded regardless of the electronic property of benzyl alcohols, and Ar?B bond remained intact throughout the reaction. Alkenyl bromides with various substitution patterns were applicable to this reaction. Attempts for utilizing sterically demanding tri-substituted alkenes indicated that the steric hinderance mainly inhibited the radical-trapping by Ni species. This reaction can be a simple and efficient strategy for synthesizing densely substituted allylbenzene derivatives. (Figure presented.).
Preparation method of heteroatom-containing cyclohexene halide
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Paragraph 0051-0053, (2019/12/25)
The invention discloses a preparation method of a heteroatom-containing cyclohexene halide, belonging to the field of synthesis of fine chemical intermediates. According to the preparation method, cyclohexanone containing heteroatoms is used as a raw material, and gem-dihalide or alkenyl halide is mainly generated in a halogenating reagent; and after an additive is added into organic alkali, and hydrogen halide is removed to generate cyclohexene halide containing heteroatoms. The method is simple in process; the operation of purifying a mixture in traditional methods is avoided; and a productis fully utilized. Under close-to-elimination condition of gem-dibromide, an additive is added to overcome the problem of difficulties in gem-dichloride elimination is by adding, and the purpose of controlling regioselectivity is achieved through steric hindrance of different alkalis.
Multimetallic Ni- and Pd-Catalyzed Cross-Electrophile Coupling to Form Highly Substituted 1,3-Dienes
Olivares, Astrid M.,Weix, Daniel J.
supporting information, p. 2446 - 2449 (2018/02/28)
The synthesis of highly substituted 1,3-dienes from the coupling of vinyl bromides with vinyl triflates is reported for the first time. The coupling is catalyzed by a combination of (5,5′-bis(trifluoromethyl)-2,2′-bipyridine)NiBr2 and (1,3-bis(diphenylphosphino)propane)PdCl2 in the presence of a zinc reductant. This method affords tetra- and penta-substituted 1,3-dienes that would otherwise be difficult to access and tolerates electron-rich and -poor substituents, heterocycles, an aryl bromide, and a pinacol boronate ester. Mechanistically, the reaction appears to proceed by an unusual zinc-mediated transfer of a vinyl group between the nickel and palladium centers.
Preparation of cyclopentyl (f) ene-1-boronic acid frequency that ester method
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Paragraph 0023, (2016/10/31)
The invention discloses a method of preparing cyclopenten/cyclohexen-1-yl-boronic acid pinacol ester from methyl 1-cyclopentene/cyclohexene-1-carboxylate by three-step continuous operations. The method includes subjecting the raw material to alkaline hydrolysis to form the corresponding 1-alkylene carboxylic acid; performing addition with bromine; performing elimination and decarboxylation at the same time under the existence of DBU or DMAP to produce 1-bromo cyclopentene/cyclohexene; and allowing the 1-bromo cyclopentene/cyclohexene and methoxyboronic acid pinacol ester to form an ester under the existence of magnesium metal by a one-pot process to obtain the cyclopenten/cyclohexen-1-yl-boronic acid pinacol ester. The method is high in continuity, simple and convenient in operations, free of low-temperature reactions, and capable of obtaining the 1-bromo cyclopentene/cyclohexene intermediate with high purity and meeting market demands. The method adopts one-pot-process of Grignard reaction/esterification, so that the method is more convenient in operations and has less by-products, and the product is easier in rectification purification.
Regioselective Synthesis of Vinyl Halides, Vinyl Sulfones, and Alkynes: A Tandem Intermolecular Nucleophilic and Electrophilic Vinylation of Tosylhydrazones
Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
, p. 18 - 21 (2015/07/28)
A diazo species is trapped in an intermolecular fashion by two independent ion species in tandem at the carbene center to install an electrophile and a nucleophile on the same carbon. This metal-free concept, which is unprecedented, has been illustrated by regioselective synthesis of a variety of vinyl halides, vinyl sulfones, and alkyne derivatives. (Chemical Equation Presented).
The continuous reaction device and method of using the continuous composite (by machine translation)
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Paragraph 0178, (2017/01/02)
PROBLEM TO BE SOLVED: compounds with high productivity can be generated. SOLUTION: 1 the raw material supply section 12 and a first, a second and 2 the raw material supply section 14, and a reaction part 18, the first reaction part 1 from the raw material supply section 1 and a second quantity of raw material, the raw material supply section 2 from the first reaction part 2 and a second quantity of raw material, the raw material supply section 1 from the first reaction part 1 and a second temperature of the raw material, the raw material supply section 2 from the first reaction part 2 and supplied to the temperature of the raw material, and having a control part 22, a continuous reaction device as shown in the drawing. Selected drawing: fig. 1 (by machine translation)
Formation of enehydrazine intermediates through coupling of phenylhydrazines with vinyl halides: Entry into the Fischer indole synthesis
Zhan, Fuxu,Liang, Guangxin
supporting information, p. 1266 - 1269 (2013/03/13)
Cut to the chase: Direct formation of an enehydrazine, an intermediate in the classic Fischer indole synthesis, solves the regioselectivity problem associated with indolization. This approach not only achieves selective synthesis of indoles through proper selection of the vinyl halide, but also leads to quick construction of desoxyeseroline and esermethole, as well as the key structural motif in the Akuammiline alkaloid vincorine. Copyright
Catalytic phosphorus(V)-mediated nucleophilic substitution reactions: Development of a catalytic appel reaction
Denton, Ross M.,An, Jie,Adeniran, Beatrice,Blake, Alexander J.,Lewis, William,Poulton, Andrew M.
experimental part, p. 6749 - 6767 (2011/10/02)
Catalytic phosphorus(V)-mediated chlorination and bromination reactions of alcohols have been developed. The new reactions constitute a catalytic version of the classical Appel halogenation reaction. In these new reactions oxalyl chloride is used as a consumable stoichiometric reagent to generate the halophosphonium salts responsible for halogenation from catalytic phosphine oxides. Thus, phosphine oxides have been transformed from stoichiometric waste products into catalysts and a new concept for catalytic phosphorus-based activation and nucleophilic substitution of alcohols has been validated. The present study has focused on a full exploration of the scope and limitations of phosphine oxide catalyzed chlorination reactions as well as the development of the analogous bromination reactions. Further mechanistic studies, including density functional theory calculations on proposed intermediates of the catalytic cycle, are consistent with a catalytic cycle involving halo- and alkoxyphosphonium salts as intermediates.
