Nicotinamide onium halide bidentate hybrid H–bond donor organocatalyst for CO2 fixation

H-bond donor (HBD) and nucleophilic halide cooperating catalysis was well developed in cycloaddition of CO 2 with epoxide (CCE) reactions where common strong HBD was prevalent. Here a type of onium halide organocatalyst featured weak C–H and N–H HBD was proposed, designed and evaluated in CCE reactions. Based on biobased nicotinamide, nicotinamidium halide catalyst was prepared by simple alkylation on pyridyl N and/or on amide NH. A mono-alkylated on pyridyl N, 1-octyl nicotinamidium iodide, was screened an optimal catalyst that achieved 96 % yield of carbonate under 1 mol% catalyst loading, 1 atm pressure of CO 2 , 80 °C, by 24 h. Terminal epoxides were converted successfully into their corresponding cyclic carbonates by 84–99 % yields with 99 % selectivity. Scale-up preparation of styrene carbonate with 100 g of styrene epoxide (by 88 % yield and 98 % selectivity), and preparation of bis(cyclic carbonate) of a commercial diglycidyl ether of bisphenol A (by 79 % yield and 98 % selectivity) showed practical utility. The H-bonding activation between C–H and N–H HBDs with epoxide was validated by 1 H NMR titrations. Designed analog catalysts to 1-octyl nicotinamidium iodide with blocked C–H or blocked N–H revealed the bidentate HBDs worked synergistically. The observations of the beneficial outcome of weak pyridium α-C–H and amide N–H H-bond donors proposed a protocol for simple yet efficient biobased H-bond donor organocatalyst development for CCE reactions. Natural product nicotinamide (vitamin B3) was formally dialkylated to render a new type of bidentate hybrid H-bond donor catalyst featured with weak C–H and N–H moieties that activated epoxide. • A bidentate hybrid C–H and N–H H-bond donor onium halide organocatalyst model was proposed. • Nicotinamidium bidentate H-bond donor catalyst was designed and evaluated in CCE reaction. • Activation of epoxide by weak C–H and N–H H-bond donors was validated by 1 H NMR titrations.