Accessing N-Stereogenicity through a Double Aza-Michael Reaction: Mechanistic Insights

Switching of the conformational flexibility of a diazacyclooctane-containing ladder polymer by coordination and elimination of a Lewis acid

We report the first system of ladder polymers capable of interconversion between rigid and flexible conformations by coordination and elimination of a Lewis acid (BPh₂Cl) on diazacyclooctane units in the main chain.

Selective synthesis of diazacyclooctane -containing flexible ladder polymers with symmetrically or unsymmetrically substituted side chains

We report a versatile synthetic method for selectively obtaining symmetrical or unsymmetrical N,N′-dialkylated DACO-containing flexible ladder polymers with various functionalities.

Rigid-to-Flexible Conformational Transformation: An Efficient Route to Ring-Opening of a Tröger's Base-Containing Ladder Polymer

The synthesis of ladder polymers is still a big challenge in polymer chemistry, and in particular, there are few examples of conformationally flexible well-defined ladder polymers. Here we report an efficient and convenient route to conformationally flexible ladder polymers, which is based on a postpolymerization reaction of a rigid ladder polymer containing Tröger's base in its main chain. The postpolymerization reaction involves sequential N-methylation and hydrolysis for the Tröger's base unit, resulting in a diazacyclooctane skeleton that can exhibit a ring-flipping motion. Molecular dynamics simulations predicted that this motion provides conformational flexibility with the resultant ladder polymer, which was demonstrated by ¹H NMR spectroscopy in solution. The presence of the diazacyclooctane units in the flexible ladder polymer allowed further functionalization through reactions involving its secondary amine moiety. The present synthetic method may lead to the development of a new class of ladder polymers that exhibit both conformational and design flexibility.