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Bicyclic molecule
About: Bicyclic molecule is a research topic. Over the lifetime, 29587 publications have been published within this topic receiving 451252 citations. The topic is also known as: bicyclic molecule.
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292 citations
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TL;DR: In this paper, the treatment of π-electron sufficient aromatic heterocycles such as title compounds with aryl bromides in the presence of tetrakis(triphenylphosphine)palladium gave the corresponding 2-aryl aromatic hetercycle.
Abstract: Treatment of π-electron sufficient aromatic heterocycles such as title compounds with aryl bromides in the presence of tetrakis(triphenylphosphine)palladium gave the corresponding 2-aryl aromatic heterocycles.
291 citations
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285 citations
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TL;DR: In the presence of a catalytic amount of Cp*RuCl(cod), 1,6-diynes chemoselectively reacted with monoalkynes at ambient temperature to afford the desired bicyclic benzene derivatives in good yields to produce meta-substituted products with excellent regioselectivity in ruthenium catalysis.
Abstract: In the presence of a catalytic amount of Cp*RuCl(cod), 1,6-diynes chemoselectively reacted with monoalkynes at ambient temperature to afford the desired bicyclic benzene derivatives in good yields. A wide variety of diynes and monoynes containing functional groups such as ester, ketone, nitrile, amine, alcohol, sulfide, etc. can be used for the present ruthenium catalysis. The most significant advantage of this protocol is that the cycloaddition of unsymmetrical 1,6-diynes with one internal alkyne moiety regioselectively gave rise to meta-substituted products with excellent regioselectivity. Completely intramolecular alkyne cyclotrimerization was also accomplished using triyne substrates to obtain tricyclic aromatic compounds fused with 5−7-membered rings. A ruthenabicycle complex relevant to these cyclotrimerizations was synthesized from Cp*RuCl(cod) and a 1,6-diyne possessing phenyl terminal groups, and its structure was unambiguously determined by X-ray analysis. The intermediary of such a ruthenacycle...
284 citations
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TL;DR: In this paper, the EPR spectrum of the colorless ABTS[sup [sm bullet][minus] ion has been examined and the standard reduction potentials of ABTS [sup 2[minus]] ion [ABTS = 2,2[prime]-azinobis(3-ethylbenzothiazoline-6-sulfonate)] have been examined since some reported values are in disagreement.
Abstract: The characteristics of the colorless ABTS[sup 2[minus]] ion [ABTS = 2,2[prime]-azinobis(3-ethylbenzothiazoline-6-sulfonate)] and of the persistent, intensely-colored radical ABTS[sup [sm bullet][minus]] have been examined since some reported values are in disagreement. The standard reduction potentials of ABTS[sup [sm bullet][minus]]/ABTS[sup 2[minus]] and ABTS[sup [sm bullet][minus]]/HABTS[sup [minus]] are 0.68 and 0.81 V vs NHE, respectively. A second wave in the CV is associated with ABTS[sup 0]/ABTS[sup [sm bullet][minus]], E[sub 1/2] = 1.09 V. The pH dependence of E[degrees] leads to pK[sub a](HABTS[sup [minus]]) = 2.2 [+-] 0.3; a spectrophotometric pH titration gives 2.08 [+-] 0.02 at [mu] = 1.0 M. The protonated radical HABTS[sup [sm bullet]] was not detected (pK[sub a] < 0), consistent with the higher acidity of the radical relative to its reduced precursor. The EPR spectrum of ABTS[sup [sm bullet][minus]] shows a multiline spectrum centered at g = 2.0036 [+-] 0.0004 from the hyperfine coupling to two sets of two equivalent nitrogens as well as six aromatic hydrogens. Line broadening of the methyl and aromatic resonances of ABTS[sup 2[minus]] in the presence of the radical gives an electron exchange rate constant of (4 [+-] 1) [times] 10[sup 7] L mol[sup [minus]] s[sup [minus]] for ABTS[sup 2[minus]]/ABTS[sup [sm bullet][minus]] in neutralmore » aqueous solution. In 1.0 M perchloric acid, Fe[sup 3+] oxidizes HABTS[sup [minus]] (k = 1.30 [times] 10[sup 2] L mol[sup [minus]1] s[sup [minus]1]) and Fe[sup 2+] reduces ABTS[sup [sm bullet][minus]] (k = 7.5 [times] 10[sup 2] L mol[sup [minus]1] s[sup [minus]1]). Although the equilibrium constant K = k[sub f]/k[sub r] for the reaction agrees with that predicted by the measured potentials, the individual rate constants are much lower than those one calculates from the Marcus cross-relation, which is typical for reactions of Fe(H[sub 2]O)[sub 6][sup 3+] and Fe(H[sub 2]O)[sub 6][sup 2+]. 28 refs., 6 figs., 2 tabs.« less
278 citations