%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 57 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