19676-33-6Relevant academic research and scientific papers
Hydrogen-Bonding-Assisted Br?nsted Acid and Gold Catalysis: Access to Both (E)- and (Z)-1,2-Haloalkenes via Hydrochlorination of Haloalkynes
Zeng, Xiaojun,Liu, Shiwen,Hammond, Gerald B.,Xu, Bo
, p. 904 - 909 (2018/02/14)
We have developed an efficient synthesis of both (Z)- and (E)-chlorohaloalkenes via hydrochlorination of haloalkynes, based on two distinct hydrogen-bond-network-assisted catalytic systems: Br?nsted acid catalysis and gold catalysis. Both systems offer high stereoselectivity, good chemical yields, and diverse functional group tolerance.
Highly stereoselective synthesis of (Z)-1,2-dihaloalkenes by a Pd-catalyzed hydrohalogenation of alkynyl halides
Zhu, Gangguo,Chen, Dongxu,Wang, Yuyi,Zheng, Renwei
supporting information; experimental part, p. 5796 - 5798 (2012/07/28)
An unprecedented Pd-catalyzed hydrohalogenation of alkynyl halides for the regio- and stereoselective synthesis of (Z)-1,2-dihaloalkenes has been realized using [(allyl)PdCl]2 as the catalyst and cis,cis-1,5-cyclooctadiene as the ligand. The advantages of this protocol are well illustrated by the assembly of trisubstituted (Z)-enynes and multifunctional benzenes via iterative cross-coupling reactions or tandem Diels-Alder-aromatization reactions, respectively.
Regio- and Stereochemistry of Bromochlorinations of Alkynes with molecular Bromine Chloride and Dichlorobromate(1-) Ion
Negoro, Takeshi,Ikeda, Yoshitsugu
, p. 3515 - 3518 (2007/10/02)
The bromochlorination of phenyl- and alkyl-substituted acetylenes with tetrabutylammonium dichlorobromate(1-) (1) in dichloromethane was found to be anti-stereospecific and nonregiospecific (regiospecific in the case of phenylacetylene).Whereas the addition of molecular bromine chloride (2) to phenyl-substituted acetylenes was found to give nonstereospecific and regiospecific adducts, the reaction of alkyl-substituted acetylenes gave anti-stereospecific and nonregiospecific adducts.These results suggest that the addition of 1 involves an attack of chloride ion to a three-centered ?-complex in the product-forming stage, and that the addition of 2 to phenyl-substituted acetylenes involves a vinyl cation intermediate (but a bridged bromonium ion intermediate in the case of alkyl-substituted acetylenes).
Nucleophilic attack on halogeno(phenyl)acetylenes by halide ions
Tanaka, Ryuichi,Zheng, Shi-Qin,Kawaguchi, Kenji,Tanaka, Takehide
, p. 1714 - 1720 (2007/10/02)
Nucleophilic reactions between halogeno(phenyl)acetylenes and halide ions, ArC≡CX + Y-, where Ar = C6H5 or p-ClC 6H4, X = Cl or Br, and Y = Cl or Br, have been examined. Halogen exchange of the Finkelstein type was observed for the first time in acetylene halides in anhydrous dimethyl sulphoxide when X = Br and Y = Cl. This exchange did not occur with other X-Y combinations. In the presence of up to 20% water in dimethyl sulphoxide, or under aqueous-organic phase-transfer catalytic conditions, nucleophilic addition (formally of HY) took place for all the X-Y combinations studied. In the additions, the nucleophile Y- invariably attacked the carbon to which the phenyl group was bound. The mode of HY addition was stereospecifically trans; accordingly, the resulting dihalogenostyrenes always had the (Z)-1,2-dihalogeno-configuration.
