- Mechanism of dehydrobromination of 1,2-dibromo-1-phenylethane under conditions of phase-transfer catalysis
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Selective dehydrobromination of 1,2-dibromo-1-phenylethane to α-bromostyrene was effected under conditions of phase-transfer catalysis in systems containing KOH, toluene, and tetraalkylammonium bromides. The high selectivity of the catalytic systems originates from stabilization by lipophilic cation of the phase-transfer catalyst of a E1cb-like transition state in the E2 mechanism. In the presence of a catalytic amount of lipophilic alcohols, phenylacetylene was obtained. Substrate activation by alcohol molecules is explained by enhancement of the acceptor power of halogen atoms due to solvation and by increased mobility of hydrogen atoms.
- Suvorova,Panicheva,Mamontova,Belyatskii
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- Nickel-Catalyzed Reductive Cross-Coupling of Vinyl Bromides with Unactivated Alkyl Halides
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The use of pyridine as the sole ligand for the reductive vinylation of unactivated secondary alkyl halides under Ni-catalyzed conditions has been developed. Both alkyl- and aryl-substituted vinyl bromides are suitable, in which alkyl-decorated α-alkenyl bromides resulted in the α-products in good results.
- Gu, Jun,Qiu, Canbin,Lu, Wenbin,Qian, Qun,Lin, Kunhua,Gong, Hegui
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- THE REACTIONS OF SOME 1,1,1-TRIBROMO-ALKYL SYSTEMS WITH THIOLATE ANIONS
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Compounds containing a 1,1,1-tribromoethyl group are normally dehydrobrominated by reaction with sodium thiolates.If a 1,1,1-tribromobut-3-ene fragment is present cyclisation to a 2,2-dibromocyclopropylmethyl thioether or rearrangement are also observed.
- Baird, Mark S.,Hoorfar, Alireza,Mitra, Manjushri
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- Transition-metal free synthesis of diaryl vinyl selenides: A simple synthetic approach with high selectivity
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A simple, highly efficient synthetic protocol is developed for the synthesis of unsymmetrical diaryl vinyl selenides from diaryldiselenide and β-bromo styrene under transition-metal free conditions in N,N′-dimethyl propylene urea and 130 °C to afford high yields and excellent selectivities. This method provides a new strategy to fabricate a wide variety of important substituted molecular skeletons and an alternative to conventionally used metal salts, additives, and ligands.
- Mohan, Balaji,Hwang, Sori,Woo, Hyunje,Park, Kang Hyun
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- Preparation of (Z)-1-halo-1-alkenes and (Z)-1-halo-2-alkoxy-1-alkenes using Cr(II/III) and Fe(0)
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Reduction of 1,1,1-trihaloalkanes by Cr(II) or Cr(III) regenerated by Fe(0) in moist tetrahydrofuran at room temperature stereoselectively generates (Z)-1-halo-1-alkenes and (Z)-1-halo-2-alkoxy-1-alkenes in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Falck,He, Anyu,Bejot, Romain,Mioskowski, Charles
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- Experimental and theoretical studies on nickel-zinc-catalyzed cross-coupling of gem-dibromoalkenes with P(O)-H compounds
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A new stereoselective one-pot protocol for the preparation of E-alkenyl-phosphorus compounds under catalysis of an inexpensive nickel-zinc catalyst system has been developed, which provides a potential useful method for C-P bond formation. 31P NMR spectrum and density functional theory calculations were performed to study the reaction mechanism.
- Liu, Liu,Lv, Ye,Wu, Yile,Gao, Xiang,Zeng, Zhiping,Gao, Yuxing,Tang, Guo,Zhao, Yufen
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- Mild regioselective monobromination of activated aromatics and heteroaromatics with N-bromosuccinimide in tetrabutylammonium bromide
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Highly regioselective nuclear bromination of activated aromatic and heteroaromatic compounds has been accomplished using N-bromosuccinimide in tetrabutylammonium bromide. Pre-dominant para-selective monobromination of activated aromatics such as phenols and anilines, rate acceleration of bromination for moderately activated and less reactive substrates on addition of acidic montmorillonite K-10 clay, with or without microwave assistance, are the notable features of this protocol.
- Ganguly, Nemai C.,De, Prithwiraj,Dutta, Sanjoy
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- Novel system for decarboxylative bromination of α,β-unsaturated carboxylic acids with diacetoxyiodobenzene
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A simple and mild method for the conversion of varieties of α,β-unsaturated carboxylic acids to the corresponding bromoalkenes using diacetoxyiodobenzene (IBD) in combination with tetraethyl-ammonium bromide (TEAB) at room temperature is discussed. Advantages of this system are short reaction time, easy work up and gave good to excellent yields.
- Fursule, Ravindra Abhykumar,Patil, Pravin Onkar,Shewale, Bharti Devaji,Kosalge, Satish Bhaskar,Deshmukh, Prashant Krishnarao,Patil, Dilip Ashok
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- Brominative Deoxygenation of Some Aldehydes and Ethers
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Three aldehydes (4a-c) are transformed into 1,1-dibromides (6a-c) by 2,2,2-tribromo-2,2-dihydro-1,3,2-benzodioxaphosphole (2).This reagent (2) is also very active in the cleavage of ethers; its reactions may show some features of carbonium as well as of SN2 character.
- Roman, Ulrich von,Knorr, Rudolf,Behringer, Claudia,Ruhdorfer, Jakob
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- Nickel-Catalyzed, Regio- and Enantioselective Benzylic Alkenylation of Olefins with Alkenyl Bromide
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A NiH-catalyzed migratory hydroalkenylation reaction of olefins with alkenyl bromides has been developed, affording benzylic alkenylation products with high yields and excellent chemoselectivity. The mild conditions of the reaction preclude olefinic products from undergoing further isomerization or subsequent alkenylation. Catalytic enantioselective hydroalkenylation of styrenes was achieved by using a chiral bisoxazoline ligand.
- Liu, Jiandong,Gong, Hegui,Zhu, Shaolin
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supporting information
p. 4060 - 4064
(2020/12/25)
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- Selective Rhodium-Catalyzed Hydroformylation of Terminal Arylalkynes and Conjugated Enynes to (Poly)enals Enabled by a π-Acceptor Biphosphoramidite Ligand
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The hydroformylation of terminal arylalkynes and enynes offers a straightforward synthetic route to the valuable (poly)enals. However, the hydroformylation of terminal alkynes has remained a long-standing challenge. Herein, an efficient and selective Rh-catalyzed hydroformylation of terminal arylalkynes and conjugated enynes has been achieved by using a new stable biphosphoramidite ligand with strong π-acceptor capacity, which affords various important E-(poly)enals in good yields with excellent chemo- and regioselectivity at low temperatures and low syngas pressures.
- Zhao, Jiangui,Zheng, Xueli,Tao, Shaokun,Zhu, Yuxin,Yi, Jiwei,Tang, Songbai,Li, Ruixiang,Chen, Hua,Fu, Haiyan,Yuan, Maolin
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supporting information
p. 6067 - 6072
(2021/08/16)
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- The hydrodebromination of 1,1-dibromoalkenes via visible light catalysis
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Vinyl bromides are versatile synthetic intermediates and widely applied in organic synthesis and pharmaceuticals. Herein, a hydrodebromination reaction of 1,1-dibromoalkenes was established via visible light catalysis. A variety of structurally different vinyl bromides were obtained in moderate to excellent yields.
- Sun, Wencheng,Teng, Qiaoling,Cheng, Dongping,Li, Xiaonian,Xu, Xiaoliang
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supporting information
(2019/12/05)
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- Dual nickel- and photoredox-catalyzed reductive cross-coupling of aryl vinyl halides and unactivated tertiary alkyl bromides
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A novel reductive cross-coupling of aryl vinyl halides and unactivated tertiary alkyl bromides has been realized via photoredox/nickel dual catalysis to produce vinyl arene derivatives bearing all-carbon quaternary centers with excellent E-selectivity. A stoichiometric metal reductant could be avoided by employing commercially available N,N,N′,N′-tetramethylethylenediamine (TMEDA) as the terminal reductant.
- Yu, Weijie,Chen, Long,Tao, Jiasi,Wang, Tao,Fu, Junkai
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supporting information
p. 5918 - 5921
(2019/05/27)
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- Construction of Phenanthrenes and Chrysenes from β-Bromovinylarenes via Aryne Diels-Alder Reaction/Aromatization
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A highly efficient transition-metal-free general method for the synthesis of polycyclic aromatic hydrocarbons like phenanthrenes and chrysenes (and tetraphene) from β-bromovinylarenes and arynes has been developed. The reactions proceed via an aryne Diels-Alder (ADA) reaction, followed by a facile aromatization. This is the first report on direct construction of chrysenes (and tetraphene) using the ADA approach. Unlike the literature method which is limited to only 9/10-substituted derivatives, this method gives access to a wide variety of functionalized phenanthrenes.
- Singh, Vikram,Verma, Ram Subhawan,Khatana, Anil K.,Tiwari, Bhoopendra
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supporting information
p. 14161 - 14167
(2019/10/28)
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- Transition metal free large-scale synthesis of aromatic vinyl chlorides from aromatic vinyl carboxylic acids using bleach
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While continuing our research on Hunsdiecker reaction, we came across an interesting application of bleach, sodium hypochlorite (NaOCl) for decarboxylative chlorination reaction. The reaction is easily scaled up to 10 mmol. The reaction has good tolerance towards wide variety of functional groups. The reaction has mild conditions and gave relatively high chemical yield of the desired product.
- Hatvate, Navnath T.,Takale, Balaram S.,Ghodse, Shrikant M.,Telvekar, Vikas N.
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p. 3892 - 3894
(2018/10/02)
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- Organic electroluminescent material and organic light emitting device
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The invention provides an organic electroluminescent material and an organic light emitting device and belongs to the technical field of organic photoelectric materials. The structure of the organic electroluminescent material contains a structure similar to carbazole; and by linking more conjugated groups, a glass transition temperature of the organic electroluminescent material can be effectively raised, the possible crystallization in use is reduced, and the ability of transporting holes is stronger. Compared with the prior art, the organic electroluminescent material is applied to the organic light emitting device and has relatively high light emitting efficiency and longer service life when being particularly used as a light emitting material.
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Paragraph 0037-0038
(2018/03/25)
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- Piperidine-appended imidazolium ionic liquid as task-specific basic-IL for Suzuki and Heck reactions and for tandem Wittig-Suzuki, Wittig-Heck, Horner-Emmons-Suzuki, and Horner-Emmons-Heck protocols
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Facile, high yielding, one-pot methods for the synthesis of a library of diversely substituted bi-aryls, diarylethenes, and aryl-enoates, via Suzuki and Heck reactions, and by sequential Wittig-Suzuki, Wittig-Heck, Horner-Emmons-Suzuki, and Horner-Emmons-Heck reactions are reported. The reactions employ piperidine-appended imidazolium ionic liquid [PAIM][NTf2] as a task-specific basic-IL, butyl-methyl-imidazolium ionic liquid [BMIM][X] (X?=?PF6, BF4) as solvent, and catalytic amounts of Pd(OAc)2 with no other additives. Wittig and Horner-Emmons reactions are effected by reacting substituted benzaldehydes with 4-bromobenzyl-PPh3 (or bromomethyl-PPh3) phosphonium salts, or diethylphosphonate with bromobenzaldehydes respectively, to form the corresponding ethenes. Subsequent cross-coupling reactions are accomplished by addition of aryl-boronic acid or phenyl-ethenes along with Pd(OAc)2 to bring about the aforementioned hyphenated transformations. The feasibility to perform double-olefination via Wittig and Horner-Emmons reactions with dialdehydes to form highly conjugated bis-styryl and bis-enoate compounds is also shown. The [BMIM][X] solvent is recycled and reused.
- Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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p. 150 - 161
(2017/06/30)
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- Pd-Catalyzed C(sp3)-C(sp2) cross-coupling of Y(CH2SiMe3)3(THF)2 with vinyl bromides and triflates
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Pd-Catalyzed C(sp3)-C(sp2) cross-coupling of Y(CH2SiMe3)3(THF)2 with vinyl bromides and triflates has been developed for efficient synthesis of various allyltrimethylsilanes. The cross-coupling reaction was conducted at room temperature with low catalyst loading of either Pd(PPh3)4 or Pd(PPh3)2Cl2, and exhibited high efficiency and a broad substrate scope. In combination with the cross-coupling by the Lewis-acid catalyzed Hosomi-Sakurai reaction, a novel three-component one-pot cascade reaction was then accomplished to deliver homoallylic alcohols and ethers with high regioselectivity and diastereoselectivity. The three-component reaction defined the yttrium complex as a novel one-carbon synthon, which could either trigger bifunctionalization of alkenes or link two electrophiles and would find applications in organic synthesis.
- Cai, Guilong,Zhou, Zhibing,Wu, Wenchao,Yao, Bo,Zhang, Shaowen,Li, Xiaofang
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supporting information
p. 8702 - 8706
(2016/10/03)
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- Ultrasonically Assisted Decarboxylative Bromination of α,β-Unsaturated Carboxylic Acids under Vilsmeier-Haack Conditions
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An efficient method for decarboxylative bromination of cinnamic acids (α,β-unsaturated carboxylic acids or 3-arylpropenoic acids) was achieved under relatively mild conditions using Vilsmeier-Haack reagent and KBr in acetonitrile media. Vilsmeier-Haack reagent is prepared by using 1:1 ratio of oxychloride (SOCl2 or POCl3) and DMF under chilled condition. Ultrasonically assisted reactions underwent smoothly with highly significant rate enhancements and afforded bromostyrenes as products in very good yields even though the reactions were too sluggish.
- Kumar, M. Satish,Rajanna,Venkanna,Venkateswarlu,Sudhakar Chary
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p. 642 - 646
(2015/12/26)
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- Palladium(0)-catalyzed cross-coupling of 1,1-diboronates with vinyl bromides and 1,1-dibromoalkenes
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Palladium-catalyzed cross-coupling reactions of 1,1-diboronates with vinyl bromides and dibromoalkenes were found to afford 1,4-dienes and allenes, respectively. These reactions utilize the high reactivities of both 1,1-diboronates and allylboron intermediates generated in the initial coupling.
- Li, Huan,Zhang, Zhikun,Shangguan, Xianghang,Huang, Shan,Chen, Jun,Zhang, Yan,Wang, Jianbo
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supporting information
p. 11921 - 11925
(2015/01/09)
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- Bromoform activation. TiCl4-Mg-promoted CHBr2 - and CBr3- transfer to a variety of aldehydes and ketones
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TiCl4-Mg can mediate addition of CHBr3 to a variety of aldehydes and ketones to form dibromomethyl carbinols and also be used to effect CBr3 transfer to carbonyl groups to form tribromomethyl carbinols. The successful application of TiCl4-Mg-promoted coupling of CHBr3 with various carbonyl compounds, especially in the case of highly enolizable ketones such as 2-indanone and β-tetralone, highlights the extraordinary reactivity and selectivity and the weakly basic nature of this system.
- Yan, Tu-Hsin,Chang, Su-Haur,Chang, Cheng-Ta,Lin, Chia-Kuan,Liu, Chien-Yu
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supporting information
p. 5802 - 5805
(2013/12/04)
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- Synthesis of 2,3,4-trisubstituted pyrroles via a facile reaction of vinyl azides and tosylmethyl isocyanide
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A facile synthesis of polysubstituted pyrroles from tosylmethyl isocyanide (TOSMIC) and readily synthesized vinyl azides was developed. The reaction proceeded under mild conditions in the presence of base. 2-Tosyl-substituted pyrroles were obtained in moderate to good isolated yields. Additionally, a base-initiated one-pot pyrrole synthesis also was developed using carboxaldehydes, ethyl 2-azidoacetate, and TOSMIC.
- Chen, Wenteng,Shao, Jiaan,Li, Zhi,Giulianotti, Marc A.,Yu, Yongping
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body text
p. 214 - 221
(2012/03/07)
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- Synthesis of acetylenes via dehydrobromination using solid anhydrous potassium phosphate as the base under phase-transfer conditions
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Phase-transfer catalyzed preparation of acetylenes from the corresponding vicinal dibromo compounds via double dehydrobromination using the mild solid base, anhydrous potassium phosphate, under very mild conditions is reported.
- Shenawi-Khalil, Sanaa,Sonavane, Sachin U.,Sasson, Yoel
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p. 2295 - 2297
(2012/07/27)
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- Regioselective copper(I)-catalyzed C-H hydroxylation/C-S coupling: Expedient construction of 2-(styrylthio)phenols
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Regioselective copper(I)-catalyzed C-H hydroxylation/C-S coupling of aryl thiols with vinyl halides was developed. Starting from substituted aryl thiols and vinyl halides, various 2-(styrylthio)phenol derivatives were efficiently prepared. The application of the synthetic methodology to generate the bioactive organic intermediate was also exemplified.
- Xu, Run-Sheng,Yue, Lei,Pan, Yuan-Jiang
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experimental part
p. 5046 - 5052
(2012/08/07)
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- A simple microwave-assisted preparation of 2-bromo-1-alkenes from 1-alkynes using the LiBr-TMSCl-TEAB reagent system
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2-Bromo-1-alkenes are cleanly and conveniently generated in good yields and selectivities via microwave-assisted hydrobromination of 1-alkynes using a combination of lithium bromide (LiBr), chlorotrimethylsilane (TMSCl), and tetraethylammonium bromide (TEAB) in acetonitrile (MeCN).
- Bunrit, Anon,Ruchirawat, Somsak,Thongsornkleeb, Charnsak
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supporting information; experimental part
p. 3124 - 3127
(2011/06/26)
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- Copper-catalyzed intermolecular oxidative [3 + 2] cycloaddition between alkenes and anhydrides: A new synthetic approach to γ-lactones
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A new copper-catalyzed oxidative [3 + 2] cycloaddition of alkenes with anhydrides using oxygen as the sole oxidant to afford γ-lactones has been developed. This catalyzed cyclization process has a broad substrate scope and affords γ-lactones in good to excellent yields.
- Huang, Liangbin,Jiang, Huanfeng,Qi, Chaorong,Liu, Xiaohang
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supporting information; experimental part
p. 17652 - 17654
(2011/03/16)
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- The concerted addition of HBr to aryl alkynes; orthogonal pi bond selectivity
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In a weakly acidic solution, the addition of HBr to 1-phenylprop-1-yne produces predominantly the anti-Markovnikov product. In this paper, we consider five possible explanations for this behavior and conclude that the concerted addition is occurring on the acetylenic π bond orthogonal to the extended aromatic π system. The electronic effect of the distal methyl group and the steric hindrance of the coplanar phenyl ring combine to promote bromide attack at the β carbon. Attack on this π bond is insensitive to the electronic effect of meta and para substituents on the ring but is very (sterically) sensitive toward all ortho substituents.
- Weiss, Hilton M.,Touchette, Kim M.,Angell, Sarah,Khan, Jihan
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p. 2152 - 2156
(2007/10/03)
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- Unexpected chemoselective debromination and reduction of 1,1-dibromo-1-alkenes mediated by samarium metal in methanol
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An unexpected samarium metal mediated chemoselective debromination and reduction of 1,1-dibromo-1-alkenes in methanol has been developed, which generates vinyl monobromides, alkenes, and alkanes respectively with appropriate molar ratio of samarium to 1,1-dibromo-1-alkene.
- Wang, Lei,Li, Pinhua,Xie, Yuanyuan,Ding, Yanbin
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p. 1137 - 1140
(2007/10/03)
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- Photochemical generation of a primary vinyl cation from (E)-bromostyrene: Mechanisms of formation and reaction
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The photochemistry of (E)-bromostyrene was investigated to determine the nature of the product-forming intermediates and to clarify the mechanism of formation of vinylic cations and vinylic radicals. Both a cation- and a radical-derived product are formed, and the ionic origin of the former product is demonstrated by significant scrambling of the label, starting from specifically deuterated (E)-bromostyrene. MO calculations show that the isolated incipient primary vinyl cation is not a metastable species, but that specific interaction with a counterion in combination with a polar environment makes it metastable. The effects of variation of the wavelength of irradiation, solvent polarity, temperature, and isotopic substitution all agree with a mechanism of direct heterolytic C-Br bond cleavage producing an ion pair followed by formation of a radical pair via electron transfer. The vinylic cation is proposed to stem directly from the indirectly populated lowest excited singlet state of bromostyrene with an energy of activation of 6.7 kcal/mol. Branching between proton loss and electron transfer in the resulting ion pair determines the ratio of cation- to radical-derived product. The E/Z-isomerization occurs in a separate process and does not involve C-Br bond cleavage.
- Gronheid, Roel,Zuilhof, Han,Hellings, Mark G.,Cornelisse, Jan,Lodder, Gerrit
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p. 3205 - 3215
(2007/10/03)
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- Study of Oxidation of Terminal Unsaturated Compounds by Reagents Based on Dimethylsulfoxide
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The products of reactions of styrene, phenylacelylene, and 1-bromo-1-phenylethane with HBr and Br2 in DMSO were studied for the first time by high-performance liquid chromatography and gas chromatography-mass spectrometry. Phenylglyoxal is the main product in the reactions with styrene and bromophenylethane, while dibromostyrenes are formed as the main products in the reaction with phenylacetylene. Schemes of the reactions of these substrates with the reagents are proposed. The reactions of nucleophilic addition and decomposition of the dimethylsulfoxonium salts formed are the key stages of the processes considered.
- Krasnokutskaya,Habicher,Yusubov,Filimonov
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p. 153 - 157
(2007/10/03)
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- Reactions of 1,1-Dihaloalkenes with Triorganozincates: A Novel Method for the Preparation of Alkenylzinc Species Associated with Carbon-Carbon Bond Formation
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Lithium trialkylzincates react with 1,1-dibromoalkenes 1 and 1-bromo-1-chloroalkenes 2 at -85 deg C in THF to give 1-bromoalkenes 5 and 1-chloroalkenes 7, respectively, upon hydrolysis.The intermediate (1-haloalkenyl)zincates 4 and 6 are stable at low temperature but, when allowed to warm to 0 deg C, they undergo a 1,2-alkyl migration reaction to afford alkenylzinc species 10.A variety of alkylation products 11 are obtained by the hydrolysis of 10.In the presence of (Ph3P)2Pd (5 molpercent), alkenylzinc species 10 react smoothly with organic halides (AcCl, EtOCOCl, CH2=CH(Me)Br, PhBr) to yield the corresponding coupling products 13-16.
- Harada, Toshiro,Katsuhira, Takeshi,Hara, Daiji,Kotani, Yasuo,Maejima, Keiji,et al.
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p. 4897 - 4907
(2007/10/02)
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- SYNTHESIS OF ARYL SUBSTITUTED EPIHALOHYDRIN DERIVATIVES
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Aryl substituted epihalohydrin derivatives were synthesized by the dehydrohalogenation of 2,3-dihalo-3-arylpropanol derivatives in the two phase solvent system of aqueous alkali solution and benzene with a phase transfer reagent such as benzyltrimethylammonium chloride.
- Yoshida, Masaaki,Hide, Tetsuro,Ohshima, Masabumi,Sasaki, Haruko,Toda, Takashi
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p. 507 - 510
(2007/10/02)
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- STEREOSELECTIVE SYNTHESIS OF (+/-)-threo-2-AMINO-1-(4-NITROPHENYL)-1,3-PROPANEDIOL
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Addition of hypobromic acid to styrene afforded styrene bromohydrin (I) which was dehydrated to ω-bromostyrene (II).Prince reaction of II with aqueous formaldehyde gave 5-bromo-4-phenyl-1,3-dioxane (III).The bromine atom in III was replaced with amino group by treatment with methanolic ammonia at 150 deg C and 6 - 8 MPa and the obtained threo-5-amino-4-phenyl-1,3-dioxane (IVa) was hydrolyzed to give (+/-)-threo-2-amino-1-phenyl-1,3-propanediol (V).Suitably chosen method of nitration converted the free base IVa or its N-acetyl derivative IVb into 5-amino-4-(4-nitrophe nyl)-1,3-dioxane (VIa) or its N-acetyl derivative VIb which without isolation were hydrolyzed to threo-2-amino-1-(4-nitrophenyl)-1,3-propanediol (VII), isolated as hydrochloride.The liberated base was resolved into enantiomers and dichloroacetylated in the known manner to give D-(-)-threo-2-dichloroacetylamino-1-(4-nitrophenyl)-1,3-propanediol (chloramphenicol).
- Cervinka, Otakar,Dudek, Vaclav,Fabryova, Anna,Kolar, Jiri,Lukac, Juraj,et al.
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p. 2748 - 2752
(2007/10/02)
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- GENERATION AND ALKYLATION REACTION OF 1-BROMOALKENYLZINCATE
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1-Bromoalkenylzincates (R1R2C=CBrZnR32Li) which are generated by the reaction of 1,1-dibromoalkenes with a lithium triorganozincate (R33ZnLi) at -85 deg C undergo alkylation reaction at temperatures from -85 deg C to 0 deg C to give alkenes R1R2C=CHR3.
- Harada, Toshiro,Hara, Daiji,Hattori, Kazuhiro,Oku, Akira
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p. 3821 - 3824
(2007/10/02)
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- Formation et stabilite des carbenoides monohalogenes β-ethers
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The β-alkoxy monohalogenated carbenoids, C6H5CH(OSiMe3)CHXLi, can be obtained by bromine-lithium exchange from the corresponding bromohaloether in the presence of s-butllithium in a mixture of THF/ether/pentane at -130 deg C.The stability of the carbenoid (α-elimination and β-elimination) is described and discussed.
- Tarhouni, R.,Kirschleger, B.,Villieras, J.
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- A PREPARATION OF BROMOOLEFINS FROM CARBONYL COMPOUNDS
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A variety of 1-bromoalkenes are prepared by addition of dibromomethyllithium to ketones and aldehydes followed by reductive elimination with zinc-acetic acid.The product E/Z ratios were determined, and halogen-lithium exchange with t-butyllithium was examined.
- Williams, David R.,Nishitani, K.,Bennett, W.,Sit, S. Y.
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p. 3745 - 3748
(2007/10/02)
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- A convenient synthesis of 1-bromoolefins and acetylenes by a chain extension of aldehydes
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Aldehydes are easily converted to 1-bromoolefins or terminal acetylenes by the use of Wittig reaction of bromomethylenetriphenylphosphorane which is prepared from bromomethyltriphenylphosphonium bromide with potassium tert-butoxide.
- Matsumoto, Masakatsu,Kuroda, Keiko
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p. 4021 - 4024
(2007/10/02)
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