%0 Journal Article
%A Levy, Amalia
%A Biedermann, P. Ulrich
%A Agranat, Israel
%D 2000
%T Interplay of Twisting and Folding in
Overcrowded Heteromerous Bistricyclic
Aromatic Enes
%U https://acs.figshare.com/articles/journal_contribution/Interplay_of_Twisting_and_Folding_in_Overcrowded_Heteromerous_Bistricyclic_Aromatic_Enes/3736065
%R 10.1021/ol005827c.s001
%2 https://acs.figshare.com/ndownloader/files/5827833
%K ΔΔ
%K 1 H NMR
%K PM
%K transition states
%K 13 C DNMR
%K kJ
%X Fluorenylidenexanthenes 5−7 were synthesized by 2-fold extrusion diazo−thione couplings. 7 exhibited yellow crystals and purple (560 nm)
solutions. 1H NMR of 5 and 7 indicated subtle equilibria twisted (t) ⇌ anti-folded (a) major/minor conformations. 13C DNMR of 6 gave
ΔGc‡(enantiomerization/inversion) = 26.5 kJ/mol and ΔGc‡(E,Z-topomerization) = 82.0 kJ/mol. PM3 calculations of 5 revealed minima a, t, ts
(twisted/syn-folded), ΔΔHf° = 0.0, 14.1, 15.6 kJ/mol, and transition states [t-ts], [a-ts], [t⊥], [a-a*], ΔΔHf° = 16.3, 17.4, 82.2, 99.3 kJ/mol.
%I ACS Publications