15022-93-2Relevant academic research and scientific papers
Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
Kumaki, Wataru,Kinoshita, Hidenori,Miura, Katsukiyo
, (2022/03/07)
Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
Visible light-mediated metal-free double bond deuteration of substituted phenylalkenes
Iakovenko, Roman,Hlavá?, Jan
, p. 440 - 446 (2021/01/28)
Various bromophenylalkenes were reductively photodebrominated by using 1,3-dimethyl-2-phenyl-1H-benzo-[d]imidazoline (DMBI) and 9,10-dicyanoanthracene. With deuterated DMBI analogs (the most effective was DMBI-d11), satisfactory to excellent isotopic yields were obtained. DMBI-d11 could also be regenerated from the reaction mixtures with a recovery rate of up to 50%. The combination of the photodebromination reaction with conventional methods for bromoalkene synthesis enables sequential monodeuteration of a double bond without the necessity of a metal catalyst. This journal is
Iridium-Catalyzed Hydrochlorination and Hydrobromination of Alkynes by Shuttle Catalysis
Yu, Peng,Bismuto, Alessandro,Morandi, Bill
supporting information, p. 2904 - 2910 (2020/01/25)
Described herein are two different methods for the synthesis of vinyl halides by a shuttle catalysis based iridium-catalyzed transfer hydrohalogenation of unactivated alkynes. The use of 4-chlorobutan-2-one or tert-butyl halide as donors of hydrogen halides allows this transformation in the absence of corrosive reagents, such as hydrogen halides or acid chlorides, thus largely improving the functional-group tolerance and safety profile of these reactions compared to the state-of-the-art. This method has granted access to alkenyl halide compounds containing acid-sensitive groups, such as tertiary alcohols, silyl ethers, and acetals. The synthetic value of those methodologies has been demonstrated by gram-scale synthesis where low catalyst loading was achieved.
HBr–DMPU: The First Aprotic Organic Solution of Hydrogen Bromide
Li, Zhou,Ebule, Rene,Kostyo, Jessica,Hammond, Gerald B.,Xu, Bo
supporting information, p. 12739 - 12743 (2017/09/25)
HBr and DMPU (1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone) form a room-temperature-stable complex that provides a mild, effective, and selective hydrobrominating reagent toward alkynes, alkenes, and allenes. HBr–DMPU could also replace other halogenating reagents in the halo-Prins reaction, ether cleavage, and deoxy-bromination reactions.
Synthesis of Highly Substituted Polyenes by Palladium-Catalyzed Cross–Couplings of Sterically Encumbered Alkenyl Bromides and N-Tosylhydrazones
Paraja, Miguel,Barroso, Raquel,Cabal, M. Paz,Valdés, Carlos
supporting information, p. 1058 - 1062 (2017/03/27)
A new method for the synthesis of polysubstituted conjugated dienes is described, through the palladium-catalyzed cross-coupling between N-tosylhydrazones and alkenyl bromides. The reaction proceeds efficiently when a combination of a highly substituted bromoalkene and a hydrazone derived from a ketone are employed, pointing to the convenience of a sterically encumbered environment. This unprecedented process allows for the stereocontrolled preparation of highly substituted dienes and polyenes. (Figure presented.).
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).
Nucleophile-selective cross-coupling reactions with vinyl and alkynyl bromides on a dinucleophilic aromatic substrate
He, Lu-Ying,Schulz-Senft, Mathias,Thiedemann, Birk,Linshoeft, Julian,Gates, Paul J.,Staubitz, Anne
supporting information, p. 2498 - 2502 (2015/04/22)
A nucleophile-selective cross-coupling reaction on an aromatic compound bearing two metal groups, Bpin and SnMe3, has been developed. Previously, only aryl bromides and iodides could be used as electrophilic components, but in this work, the scope could be extended to vinyl and alkynyl bromides as electrophiles. This means that the roles typical in Sonogashira couplings or Heck reactions of the aromatic ring as the dielectrophile coupling to vinyl and alkynyl metal species are reversed, which presents a new tool for organic synthesis. The first nucleophilic site to react is the stannyl group, and subsequently, a Suzuki-Miyaura cross-coupling reaction can take place on the same molecule.
Metal-free regioselective hydrobromination of alkynes through CH/CBr activation
Chen, Xiuling,Chen, Tieqiao,Xiang, Yuqiang,Zhou, Yongbo,Han, Daoqing,Han, Li-Biao,Yin, Shuang-Feng
supporting information, p. 4572 - 4575 (2014/12/10)
A metal-free regioselective hydrobromination of alkynes has been developed to provide the Markovnikov-type vinyl bromides in good yields using dibromomethane/N,N-dimethylaniline as in-situ 'HBr' source. This protocol also represents an elegant example of the activation of sp2 CH and CBr bonds in one pot, in which 'HBr' is generated and transferred under mild metal-free conditions. D-incorporated experiments were employed to investigate the reaction mechanism and a plausible reaction path was proposed.
Radical-chain oxidative addition mechanism for the reaction of an [Re(CO)5]- anion with α-bromostilbene
Sazonov, Petr K.,Ptushkin, Dmitry S.,Khrustalev, Victor N.,Kolotyrkina, Natal'Ya G.,Beletskaya, Irina P.
, p. 4223 - 4232 (2013/04/23)
E-α-Bromostilbene spontaneously reacts with Na[Re(CO)5] at 22 °C in THF to give Na[ReBr(CO)4{Z-C(Ph)CHPh}] and Na[Re 2(CO)9{Z-C(Ph)CHPh}] as the main products. Z-α-Bromostilbene is less reactive, but gives the same products. The reaction is stimulated by visible light or a source of solvated electrons (NaK2.8) and can be inhibited by a quinomethide radical trap. With an excess of Na[Re(CO)5] one can observe the initial formation of Na[ReBr(CO)4{Z-C(Ph)CHPh}] and its complete transformation into Na[Re2(CO)9{Z-C(Ph)CHPh}]. Treatment of Na[ReBr(CO) 4{Z-C(Ph)CHPh}] with CO almost quantitatively converts it to [Re(CO)5{Z-C(Ph)CHPh}], the structure of which is established by a single-crystal X-ray diffraction study. A radical-chain mechanism is proposed for the reaction comprising the following steps: (a) coupling of a Vin radical with Na[Re(CO)5], (b) CO-dissociation from the formed 19-electron radical-anion and (c) bromine atom abstraction by [Re(CO)4{Z-C(Ph) CHPh}]- from α-bromostilbene. The mechanism is confirmed by the formation of the same Na[ReBr(CO)4{Z-C(Ph)CHPh}] product in the presence of NaI. When the radical-chain process is inhibited, a slow halogenophilic reaction is observed, mainly giving the Z and E-isomers of the acylrhenate Na[Re2(CO)9{C(O)C(Ph)CHPh}].
Palladium-catalysed cross-coupling reactions of triorganoindium reagents with alkenyl halides
Riveiros, Ricardo,Saya, Lucia,Sestelo, Jose Perez,Sarandeses, Luis A.
experimental part, p. 1959 - 1966 (2009/04/03)
The regio- and stereoselectivity of the palladium-catalysed cross-coupling reactions of indium organometallics with stereodefined 1-haloalkenes and 1,1-dihaloalkenes have been studied. Triorganoindium reagents (R3In; R = alkyl, alkenyl, aryl an
