Synthesis of Single‐Handed Helical Spiro‐Conjugated Ladder Polymers through Quantitative and Chemoselective Cyclizations**

Abstract

We report the unprecedented synthesis of onehanded helical spiro-conjugated ladder polymers with welldefined primary and secondary structures, in which the spirolinked dibenzo [a,h]anthracene fluorophores are arranged in a one-handed twisting direction, through quantitative and chemoselective acid-promoted intramolecular cyclizations of random-coil precursor polymers composed of chiral 1,1'spirobiindane and achiral bis[2-(4-alkoxyphenyl)ethynyl]phenylene units. Intense circular dichroism (CD) and circularly polarized luminescence (CPL) were observed, whereas the precursor polymers exhibited negligible CD and CPL activities. The introduction of 2,6-dimethyl substituents on the 4alkoxyphenylethynyl pendants is of key importance for this simple, quantitative, and chemoselective cyclization. This strategy is applicable to the defect-free precise synthesis of other varieties of fully p-conjugated molecules and coplanar ladder polymers that have not been achieved before.

Synthesis of Single‐Handed Helical Spiro‐Conjugated Ladder Polymers through Quantitative and Chemoselective Cyclizations**

“…Ellipsoids are set at 50 % probability. [18] D) 1 H NMR spectra (500 MHz, CDCl 3 , 258C) of (R)-1 H (i), (R)-1 Me (iii), and as-synthesized cyclization products obtained from (R)-1 H (ii) and (R)-1 Me (iv). For the signal assignments and the corresponding IR spectra, see the Supporting Information, Figures S1-S4 and S5A-D, respectively.…”

“…C) X-ray crystal structure of (R)-2 Me . Ellipsoids are set at 50 % probability [18]. D) 1 H NMR spectra (500 MHz, CDCl 3 , 258C) of (R)-1 H (i), (R)-1 Me (iii), and as-synthesized cyclization products obtained from (R)-1 H (ii) and (R)-1 Me (iv).…”

Symmetrically Tetra‐functionalized Pillar[6]arenes Prepared by Fragment Coupling

“…Iodoarenes are generally considered more reactive than bromoarenes in Pd‐catalyzed reactions. There is substantial literature showing that converting an iodine group precedes a bromine group on the same molecule during Pd‐catalyzed reactions, and therefore sequential functionalization could be achieved [56–58] . This precedence is widely used in synthesizing π‐extended molecules and unsymmetrical ligands to construct metal–organic cages or macrocycles [59–62] .…”

Optimization of an Asymmetric Reaction in the Cavity of Chiral Aromatic Oligoamide Foldamers

“…Onehanded helical preferred systems have been successfully applied in areas such as chiral recognition, [11][12][13] asymmetric reactions, [14][15][16][17] and circularly polarized luminescence (CPL)active material. [18] For asymmetric reactions, the stereoselectivity is dependent on the chiral and steric backbones of oligomers that mainly react with substrates on the end, [14,19] or side of the chain, [20] whereas analogous reactions occurring in their cavities have rarely been reported. In comparison, the biochemical reactions of proteins occur in their folded pockets where the substrate can interact with multiple active sites and be forced to adopt a specific orientation, from which high efficiency and specificity are derived.…”