1,3-Dipolar and Diels-Alder cycloaddition reactions on polyester backbones possessing internal electron-deficient alkyne moieties

In this study we prepared a series of polyesters containing electron deficient internal alkyne units derived from acetylene dicarboxylic acid in the main backbone. Next, one of the polyesters was employed as a polymeric platform in copper free cycloaddition reactions like, Huisgen type 1,3-dipolar and Diels-Alder cycloaddition reactions in the presence of various dipoles and dienes, respectively. The 1,3-dipolar cycloaddition reactions were performed at mild temperatures (rt and 40 °C) in 1,4-dioxane for 16 h and had moderately high efficiencies (80-100%). However, the Diels-Alder cycloaddition reactions were carried out at higher temperatures (60 to 120 °C) in 1,4-dioxane for 16 h with reasonable efficiencies (45-97%). Moreover, the polyester was successfully used in one-pot 1,3-dipolar, sequential 1,3-dipolar/Diels-Alder, and sequential 1,3-dipolar cycloaddition/retro-Diels-Alder reactions

Propiolated Castor Oil: A Novel and Highly Versatile Bio-Based Platform for Extremely Fast, Catalyst‑, and Solvent-Free Amino-yne Click Reactions

The quest for sustainable monomers and “green” synthetic pathways for the design, fabrication, and modification of various polymers is of great importance and attracts a great deal of attention. Here, a highly versatile and novel bio-based platform was developed by reacting castor oil with propiolic acid for performing amino-yne click reactions. Owing to the electron-deficient nature of the propiolic acid esters, amino-yne click reactions were conducted with ease at room temperature, in the absence of any catalyst and solvent (as long as the amines were low-viscosity liquids at room temperature), and within 5 min. Several primary and secondary amines were shown to react readily with the developed platform. Furthermore, thermosets were prepared by using the propiolated castor oil and multifunctional amines. The prepared thermosets displayed improved thermal properties and elastomer-like mechanical properties