Synthesis of a Chiral Non-Racemic Segmented Screw-Like Oligomer. An Unusual Form of Molecular Chirality
SOUTH CAROLINA UNIV COLUMBIA DEPT OF CHEMISTRY AND BIOCHEMISTRY
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Described is the synthesis of a chiral non-racemic conjugated organic oligomer that possesses a linear backbone but has segmented helical functional groups emanating from the backbone. Both antipodes were independently synthesized. The monomer is based upon a chiral non-racemic binaphthalene core with p-bromophenyl groups at the 4 and 4-positions of the binaphthalene. The monomer was prepared using successive bisorthometallation reactions on chiral non-racemic binaphthol. The p-bromophenyl groups were affixed via a Pd0- catalyzed cross coupling of 1,4-dibromobenzene and the 4,4-bisboronic ester of the binaphthalene. The final oligomerization was affected by a Ni0-promoted coupling of the arylbromides. The new oligomeric framework demonstrates that even highly aligned chiral groups along a common axis are insufficient for large optical rotational enhancements if there is no repeat unit registry.
- Organic Chemistry
- Physical Chemistry
- Polymer Chemistry
- Atomic and Molecular Physics and Spectroscopy