Modification of electron deficient polyester via Huisgen/Passerini sequence

In this work, we functionalized a polyester backbone via sequential Huisgen 1,3-dipolar cycloaddition and 3-component Passerini reactions. First, we directly introduced the carboxyl acid functionality onto the electron deficient polyester using Huisgen 1,3-dipolar cycloaddition protocol in N,N-dimethyl formamide at 40 °C for 16 h. This acid functional polyester was further modified by Passerini reaction using two types of isocyanides and a variety of aldehydes in CH₂Cl₂ at room temperature for 24 h. Both protocols are atom economic, highly efficient, need no additional catalyst and proceed at ambient temperature. The products were characterized using spectroscopic and chromatographic techniques such as NMR, IR and GPC, respectively.