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Nickel catalyzed synthesis of 4,4′-bichromenes/4,4′-bithiochromenes and their Atropisomerism
Jai Anand Garg, Kalapattukuppuswamy Kuppuswamy B. Balasubramanian
Published in Royal Society of Chemistry
2019
Volume: 6
   
Issue: 1
Pages: 134 - 139
Abstract
Axially chiral molecules have established undisputed importance in both medicinal chemistry and enantiomeric catalysis. The size, shape and hybridization of the substituent adjacent to the rotational axis greatly dictate atropisomerism. Herein, we examined the tropoisomeric behavior of 4,4′-bichromenes and 4,4′-bithiochromenes derivatives that were synthesized by a nickel catalyzed reductive homocoupling strategy. The as-synthesized 3,3′-disubstituted 4,4′-bichromenes displayed atropisomerism, as evidenced by chiral stationary phase HPLC, electronic circular dichroism and single crystal XRD studies. Insights into the torsional barrier about the internuclear axis in 4,4′-bichromenes were gained both experimentally and theoretically (DFT studies). The lower activation energy barrier (Ea) of approximately 12 kcal mol-1 as compared to that of fully aromatic 1,1′-binapthyl explains the conformationally unstable nature of 3,3′-unsubstituted 4,4′-bichromenes at room temperature. © the Partner Organisations.
About the journal
JournalData powered by TypesetOrganic Chemistry Frontiers
PublisherData powered by TypesetRoyal Society of Chemistry
ISSN20524110
Open AccessNo
Concepts (14)
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    Activation energy
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    Catalysis
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    Dichroism
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    Nickel
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    Single crystals
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    CATALYZED SYNTHESIS
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    CHIRAL STATIONARY PHASE
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    ELECTRONIC CIRCULAR DICHROISM
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    INTERNUCLEAR AXIS
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    Medicinal chemistry
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    ROTATIONAL AXIS
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    Single crystal xrd
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    Torsional barriers
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    Stereochemistry