Synthesis and Properties of Partially Saturated Fluorenyl-Derived [n]helicenes Featuring an Overcrowded Alkene - Archive ouverte HAL Access content directly
Journal Articles Chemistry - A European Journal Year : 2021

Synthesis and Properties of Partially Saturated Fluorenyl-Derived [n]helicenes Featuring an Overcrowded Alkene

Abstract

The straightforward, multigram-scale synthesis of the partially saturated H -fluoreno[n]helicenes (n=5 or 7) featuring a central, overcrowded alkene is described. The key cyclization step was based on an intramolecular McMurry reaction from the corresponding 1,5-diketones. Chiral stationary phase HPLC analysis and isomer separation indicate that each helicenic compound is constituted of three diastereoisomers at room temperature, i. e. the configurationally stable (R,R,P)/(S,S,M) pair of enantiomers and an apparently achiral compound resulting from the rapid interconversion between the (R,S,P) and (S,R,M) enantiomers. The partially saturated H -fluoreno[n]helicenes are oxidatively aromatized to give an efficient access to the corresponding fluoreno[n]helicenes. The chiroptical properties (vibrational and electronic circular dichroism) of the chiral, enantiopure compounds have been measured and analyzed by quantum-chemical calculations, confirming their helicoidal nature.
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Dates and versions

hal-03194360 , version 1 (22-04-2021)

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Lenka Pallova, Etienne Gauthier, Laura Abella, Marion Jean, Nicolas Vanthuyne, et al.. Synthesis and Properties of Partially Saturated Fluorenyl-Derived [n]helicenes Featuring an Overcrowded Alkene. Chemistry - A European Journal, 2021, 27 (28), pp.7722-7730. ⟨10.1002/chem.202100150⟩. ⟨hal-03194360⟩
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