The First Enantiomerically Pure Triangulane (M)-Trispiro
A remarkably high specific rotation, even at 589 nm, is shown by (M)-1, the first enantiomerically pure unbranched [4]triangulane, although it has no chromophore that would lead to any significant absorption above 200 nm. This outstanding rotatory power is in line with a helical arrangement of its sigma bonds, as confirmed by high-level computations. Thus, it is appropriate to call (M)-1 a "sigma-[4]helicene", the first sigma-bond analogue of the aromatic [n]helicenes.
de Meijere A
Institut für Organische Chemie der Universität, Tammannstrasse 2, D-37077 Göttingen (Germany).
Khlebnikov
AF
Kostikov
RR
Kozhushkov
SI
Schreiner
PR
Wittkopp
A
Yufit
DS