Poly(ε-caprolactones) Initiated by Chiral Compounds: A New Protocol to Support Organocatalysts

Abstract

This work investigates the support of organocatalysts in polyesters, a class of polymers seldom used for this purpose. The proposal is to use the hydroxyl groups present in the structure of the chosen chiral compounds to promote the polymerization of ε-caprolactone, generating the support and anchoring the organocatalyst in a single step. A very simple method, with acid catalysis, was employed, that showed versatility in generating supported catalysts with different structures and functional groups and modulating the mass of the materials to generate specific solubility characteristics. In this way, the catalysts can be solubilized in some organic solvents, such as dichloromethane, but at the end of the reaction, they can be recovered in a heterogeneous way, through precipitation in more apolar solvents. The materials were applied as organocatalysts on an aldol addition test reaction and the product could be obtained in excellent yields and good stereoselectivity. The polymer did not show signs of degradation after the reaction, proving to be robust and suitable for use in catalysis; however, a recycling process appears to be necessary for its reuse.