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Updated: Aug 4, 2026

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Interplay of Twisting and Folding in Overcrowded Heteromerous Bistricyclic Aromatic Enes
1Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Abstract:
Fluorenylidenexanthenes 5-7 were synthesized by 2-fold extrusion diazo-thione couplings. 7 exhibited yellow crystals and purple (560 nm) solutions. (1)H NMR of 5 and 7 indicated subtle equilibria twisted (t) right harpoon over left harpoon anti-folded (a) major/minor conformations. (13)C DNMR of 6 gave DeltaG(c)(double dagger)(enantiomerization/inversion) = 26.5 kJ/mol and DeltaG(c)(double dagger)(E,Z-topomerization) = 82.0 kJ/mol. PM3 calculations of 5 revealed minima a, t, ts (twisted/syn-folded), DeltaDeltaH(f) degrees = 0.0, 14.1, 15.6 kJ/mol, and transition states [t-ts], [a-ts], [t( perpendicular)], [a-a], DeltaDeltaH(f) degrees = 16.3, 17.4, 82.2, 99.3 kJ/mol.
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