- An Alternative Synthesis of Cycloalkyl-Substituted CPA Catalysts and Application in Asymmetric Protonation Reactions**
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An alternative synthesis of cycloalkyl-substituted CPA catalysts is reported. A Negishi coupling offers improved yields and purity of the necessary 1,3,5-tri(cycloalkyl)benzenes. Limitations in the use of commercial organozinc reagents have been identifie
- McLean, Liam A.,Watson, Allan J. B.
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p. 4943 - 4945
(2021/09/28)
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- Iron-catalyzed regioselective cyclotrimerization of alkynes to benzenes
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We report the synthesis and characterization of simple di(aminomethyl)pyridine ligated iron-pincer complexes, which catalyzed the regioselective [2+2+2] cyclotrimerization of terminal aryl and alkyl alkynes to provide the 1,2,4-trisubstituted benzene molecules. Interestingly, internal alkynes also exhibited similar cyclization and resulted in hexa-substituted benzene compounds. Increased steric bulk on pincer ligands diminished the selectivity for cycloaddition. Cyclotrimerization reactions proceeded at room temperature upon activation of catalyst by a Grignard reagent. EPR studies indicated thermally induced spin crossover effect in catalyst.
- Gawali, Suhas Shahaji,Gunanathan, Chidambaram
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p. 139 - 149
(2019/01/03)
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- Benzene Alkylation with Cycloolefins under the Action of [Et3NH]+[Al2Cl7]? Ionic Liquid
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Benzene alkylation with mono- and bicyclic olefins under the action of an inorganic ionic liquid [Et3NH]+[Al2Cl7]? with the formation of benzene cycloalkyl derivatives in 58–98% yield has been performed for the first time. It has been found that the increase in the olefin cycle size improves the selectivity with respect to monocycloalkyl derivatives.
- Aminov,Mazitova,Khusnutdinov
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p. 2171 - 2177
(2020/01/08)
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- Enantioselective halogenative semi-pinacol rearrangement: Extension of substrate scope and mechanistic investigations
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The present Full Paper article discloses a survey of our recent results obtained in the context of the enantioselective halogenation-initiated semi-pinacol rearrangement. Commencing with the fluorination/semi-pinacol reaction first and moving to the heavier halogens (bromine and iodine) second, the scope and limitations of the halogenative phase-transfer methodology will be discussed and compared. An extension of the fluorination/semi-pinacol reaction to the ring-expansion of five-membered allylic cyclopentanols will be also described, as well as some preliminary results on substrates prone to desymmetrization will be given. Finally, the present manuscript will culminate with a detailed mechanistic investigation of the canonical fluorination/semi-pinacol reaction. Our mechanistic discussion will be based on in situ reaction progress monitoring, complemented with substituent effect, kinetic isotopic effect and non-linear behaviour studies.
- Romanov-Michailidis, Fedor,Romanova-Michaelides, Maria,Pupier, Marion,Alexakis, Alexandre
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supporting information
p. 5561 - 5583
(2015/03/30)
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- Metal complexes of very bulky N,N′-diarylimidazolylidene N-heterocyclic carbene (NHC) ligands with 2,4,6-cycloalkyl substituents
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1,3,5-Tricycloalkylbenzene (cycloalkyl = C5H9, C6H11) was converted into the respective anilines (by means of nitration and reduction) and then into the corresponding diimines (with glyoxal), the cyclization of
- Savka, Roman,Plenio, Herbert
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p. 6246 - 6253
(2015/02/19)
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- Enantioselective organocatalytic iodination-initiated Wagner-Meerwein rearrangement
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The present manuscript describes a high-yielding enantioselective semipinacol transposition, initiated by an electrophilic iodination event. The title transformation makes use of the anionic phase-transfer catalysis (PTC) paradigm for chirality induction. Thus, when combined appropriately, the insoluble cationic iodinating reagent S9 and the lipophilic phosphoric acid L9 act as an efficient source of chiral iodine that performs the semipinacol transposition of strained allylic alcohols A x to β-iodo spiroketones Bx in good yields and with high levels of diastereo- and enantio-induction. The product β-iodo spiroketones could be derivatized stereospecifically and without stereoerosion, giving rise to products inaccessible directly from a semipinacol rearrangement.
- Romanov-Michailidis, Fedor,Guenee, Laure,Alexakis, Alexandre
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supporting information
p. 5890 - 5893
(2013/12/04)
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- Enantioselective organocatalytic fluorination-induced Wagner-Meerwein rearrangement
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Cracked under strain: Strained allylic cyclobutanols and cyclopropanols readily undergo a ring expansion described by the title rearrangement. This reaction is promoted by catalytic amounts of 1 and displays high tolerance with respect to the substrate scope. The corresponding β-fluoro spiroketone products are isolated in high yields and with excellent stereoselectivities. EDG=electron-donating group, EWG=electron-withdrawing group. Copyright
- Romanov-Michailidis, Fedor,Guénée, Laure,Alexakis, Alexandre
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supporting information
p. 9266 - 9270
(2013/09/12)
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- A new biarylphosphine ligand for the Pd-catalyzed synthesis of diaryl ethers under mild conditions
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A new bulky biarylphosphine ligand (L8) has been developed that allows the Pd-catalyzed C-O cross-coupling of a wide range of aryl halides and phenols under milder conditions than previously possible. A direct correlation between the size of the ligand substituents in the 2′, 4′, and 6′ positions of the nonphosphine containing ring and the reactivity of the derived catalyst system was observed. Specifically, the rate of coupling increased with the size of these substituents.
- Salvi, Luca,Davis, Nicole R.,Ali, Siraj Z.,Buchwald, Stephen L.
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supporting information; experimental part
p. 170 - 173
(2012/03/08)
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