704-77-8Relevant academic research and scientific papers
Conceptual approach to the synthesis of symmetrical 1,3-diynes from β-bromo vinyl carboxylic acids
Singha, Raju
, (2020/01/09)
Abstract: A conceptual route has been developed for the synthesis of 1,3-diyne from β-bromo vinyl carboxylic acids. The reaction of the β-bromo vinyl carboxylic acid with palladium catalyst is conceptually similar to the decomposition of 2-diazoniumbenzoic acid to benzyne. In the presence of palladium catalyst, the β-bromo vinyl carboxylic acid undergoes a fragmentation to generate terminal alkyne. The terminal alkyne undergoes dimerisation in the presence of palladium catalysts to produce the product 1,3-diyne. Graphic abstract: A conceptual route has been developed for the synthesis of 1,3-diyne from β-bromo vinyl carboxylic acids. To the best of our knowledge, we are the first ones reporting the synthesis of 1,3-diyne in a catalytic way without the requirement of any prefunctionalized alkyne unit(s).[Figure not available: see fulltext.]
Metal-Free Transfer Hydrobromination of C-C Triple Bonds
Chen, Weiqiang,Oestreich, Martin
supporting information, p. 4531 - 4534 (2019/06/27)
A transfer hydrobromination of C-C triple bonds inititated by Br?nsted acids is reported. Hydrogen bromide is released stepwise from a bench-stable cyclohexa-1,4-diene-based surrogate, generating biphenyl and ethylene as waste. A range of vinyl bromides was prepared from terminal and internal, mainly acceptor-substituted alkynes with good functional-group tolerance.
Divergent NHC-catalyzed oxidative transformations of 3-bromoenal: Selective synthesis of 2H-pyran-2-ones and chiral dihydropyranones
Wang, Gang,Chen, Xia,Miao, Gaohan,Yao, Weijun,Ma, Cheng
, p. 6223 - 6232 (2013/07/26)
A selective synthesis of either 2H-pyran-2-ones (4) or chiral dihydropyranones (6) from the same substrates of 3-bromoenals and 1,3-dicarbonyl compounds upon oxidative N-heterocyclic carbene catalysis is presented. It is shown that the oxidative transformation of 3-bromoenals under NHC catalyst can be well controlled to proceed through two pathways, i.e., elimination of reducible β-bromide or by an external oxidant 3, allowing the selective generation two sorts of unsaturated acyl azoliums, respectively.
Controlling 6-endo-selectivity in oxidation/bromocyclization cascades for synthesis of aplysiapyranoids and other 2,2,6,6-substituted tetrahydropyrans
Brücher, Oliver,Bergstr??er, Uwe,Kelm, Harald,Hartung, Jens,Greb, Marco,Svoboda, Ingrid,Fuess, Hartmut
supporting information; experimental part, p. 6968 - 6980 (2012/09/07)
A cascade, composed of (i) oxovanadium(V)-catalyzed oxidation of bromide by tert-butyl hydroperoxide and (ii) stereoselective 6-endo-bromocyclization, affords 3-bromo-2-aryl-2,6,6-trimethyltetrahydropyrans from styrene-type tertiary alkenols in synthetically useful yields. (E)-Alkenols add the bromo- and the alkoxy substituent anti-selectively across the double bond, indicating a bromonium ion-mechanism for the ring closure. 6-endo-control of the alkenol cyclization thereby arises from the polar effect of the aryl substituent. Two methyl substituents bound to the alkene terminus are not similarly able to favor 6-endo-cyclization, because strain arising from methyl group repulsion, as the bromonium-activated π-bond and the hydroxyl oxygen approach, directs bromocyclization of tertiary prenyl-type substrates toward tetrahydrofuran formation. A hexasubstituted bromotetrahydropyran prepared from the oxidation/bromocyclization cascade served as starting material for synthesis of racemic aplysiapyranoid A, in a sequence of free radical and polar functional group interconversion.
In search of the spin-delocalization effect from the correlation analysis of relative rates of the trichloromethyl-bromo-addition reactions to fourteen p-Y-substituted phenylacetylenes
Jiang, Xi-Kui,Ji, Guo-Zhen,Xie, John Rong-Yuan
, p. 3017 - 3028 (2007/10/03)
A rigorous procedure was applied to the measurement of the relative rates, i.e. k(r)(Y) = k(Y)/k(H) of trichloromethyl-bromo-addition reactions to fourteen p-Y-substituted phenylacetylenes (I-Y, with Y = F, Cl, Br, Me, t-Bu, OMe, SMe, SiMe3, CF3, CN, NO2, SOMe, COMe, and CO2Me). The reaction was run in cyclohexane under nitrogen antmosphere at 65 ± 0.5°C. All products were derived from the intermediate YC6H4C = CHCCl3 adduct radicals. Correlation analysis of these rate data seems to suggest that both a polar and a spin-delocalization effect are operating at the transition state.
A CONTRIBUTION TO MECHANISM OF ADDITION OF HYDROGEN BROMIDE TO THE α,β-UNSATURATEDSYSTEM OF 3-PHENYL-2-PROPENOIC ACID
Cervinka, Otakar,Kriz, Otomar
, p. 2952 - 2964 (2007/10/02)
Rate of addition of hydrogen bromide to meta- and para-substituted 3-phenyl-2-propenoic acids I was followed by polarography and UV spectroscopy.Rate of protonation either is the overall rate determining step or is at least comparable with the rate of the subsequent nucleophile attack.
