704-78-9Relevant 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.
Highly efficient and selective procedures for the synthesis of γ-alkylidenebutenolides via palladium-catalyzed ene-yne coupling and palladium- or silver-catalyzed lactonization of (Z)-2-en-4-ynoic acids. Synthesis of rubrolides A, C, D, and E
Kotora, Matin,Negishi, Ei-Ichi
, p. 121 - 128 (2007/10/03)
The diacetates of rubrolides A, C, D, and E (1 a-d) were prepared in modest yields by the Pd-catalyzed cross coupling-lactonization tandem reaction of 5a or 5b with 6a or 6b using Cl2Pd(PPh3)2 and CuI as catalysts. The feasibility of converting the diacetates into rubrolides was demonstrated by the synthesis of rubrolide C by treatment of 1b with methanolic K2CO3 in THF. A detailed investigation of various parameters and conditions has indicated that formation of the corresponding six-membered lactones 7 and/or the cross coupling-lactonization-Heck substitution products 11 can be serious side reactions under non-optimized conditions and that the use of Pd(PPh3)4 rather than phosphine-free complexes, e.g., CI2Pd(PhCN)2, or complexes of low phosphine content, e.g., Cl2Pd(PPh3)2, along with CuI and NEt3 in MeCN provides satisfactory conditions for the cross coupling-lactonization tandem reaction. Thus, the diacetate of rubrolide A (1a) was prepared in 70% isolated yield. The optimized conditions reported herein appear to be generally applicable to the stereoselective and regioselective synthesis of γ-alkylidenebutenolides in a highly efficient manner.
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.
