Geländer Molecules with Orthogonal Joints: Synthesis of Macrocyclic Dimers
Adriano D'Addio, Juraj Malinčík, Olaf Fuhr, Dieter Fenske, Daniel Häußinger, Marcel Mayor
Abstract
Abstract Orthogonal joints, understood as connections with an angle of 90°, were introduced in the design of the “Geländer” model compounds 1 and 2 . The banister, consisting of a conjugated carbazole dimer linked by either 1,3‐butadiyne ( 2 ) or a single thiophene ( 1 ), wraps around an axis composed of a phthalimide dimer due to the dimensional mismatch of both subunits, which are interconnected by phenylene rungs. The “Geländer” structure was assembled from a monomer comprising the 1,4‐diaminobenzene rung with one amino substituent as part of a 4‐bromo phthalimide subunit forming the orthogonal junction to the axis, and the other as part of a masked 2‐ethynyl carbazole as orthogonal joint to the banister. The macrocycle was obtained by two sequential homocoupling steps. A first dimerization by a reductive homocoupling assembled the axis, while an oxidative acetylene coupling served as ring‐closing reaction. The formed butadiyne was further derivatized to a thiophene, rendering all carbons of the model compound sp 2 hybridized. Both helical structures were fully characterized and chirally resolved. Assignment of the enantiomers was achieved by simulation of chiroptical properties and enantiopure synthesis.