open access

https://hdl.handle.net/2115/65206

Dynamic helical cyclophanes with two quadruply-bridged planes arranged in an "obverse and/or reverse" relation

英語

2016-05-01

Royal Society of Chemistry

Chemical science

7(5)

3240-3247

We describe the design of two types of cyclophanes that generate dynamic helicity through the twisting of two planes in a clockwise or counterclockwise direction to give (M)- or (P)-helicity. We used a rectangular and anisotropic plane of 1,2,4,5-tetrakis(phenylethynyl) benzene (TPEB), since it can be stacked in pairs in two ways, in parallel or orthogonally, to be identified as distinct cyclophane molecules. We adopted a synthetic strategy for obtaining these two cyclophanes as a mixture using a macrocyclic intermediate that possessed two rotatable phenyl rings. We introduced necessary parts into the rotators to give a mixture of rotational isomers leading to a parallel or orthogonal arrangement of TPEBs, and then doubly bridged two planes of TPEB to form quadruply-bridged cyclophanes. We consider that such two planes in each cyclophane are in an "obverse and/or reverse" relation. In each cyclophane, we found unique dynamic helical forms with (M)- or (P)-helicity as well as an inherently non-chiral form. Normally, the screw-sense preference of dynamic helicity would be controlled through the intramolecular or supramolecular transmission of central chirality, when a chiral auxiliary is attached to the cyclophanes or a chiral guest is allowed to form a complex with the cyclophanes. In a case where two different substitution groups were used on bridging units to generate planar chirality in each cyclophane, the screw-sense preference was controlled through the arrangement of these substitution groups, and did not depend on the transmission of central chirality. Two different substitution groups desymmetrize the enantiomeric forms with (M)- or (P)-helicity generated in each dynamic helical cyclophane so that two dynamic helical forms with (M)- or (P)-helicity can be in a diastereomeric relation. Thus, a particular screw sense of dynamic helicity can be preferred, regardless of whether or not the two substitution groups possess some chiral element.

学術雑誌論文

Version of Record

Creative Commons Attribution 3.0 Unported

2041-6520

AA12555653