Carbon dioxide is a renewable, inexhaustible, and cheap alternative to fossil resources for the production of fine chemicals and plastics. It can notably be converted into exovinylene cyclic carbonates, unique synthons gaining momentum for the preparation of an impressive range of important organic molecules and functional polymers, in reactions proceeding with 100 % atom economy under mild operating conditions in most cases. This Review summarizes the recent advances in their synthesis with particular attention on describing the catalysts needed for their preparation and discussing the unique reactivity of these CO2‐based heterocycles for the construction of diverse organic building blocks and (functional) polymers. We also discuss the challenges and the future perspectives in the field.

The synthesis of α‐alkylidene cyclic carbonates (αCCs) by the carboxylative coupling of CO2 with propargylic alcohols is receiving increasing interest but requires the use of catalysts that are most often added in large quantities and/or lack selectivity. Herein, we describe the fine‐tuning of the structure of organocatalysts of the ammonium‐type that enables us to identify the important structural parameters that dictate their catalytic performance. Tetrabutylammonium oxalate was revealed to be one of the most attractive organocatalysts with a remarkably fast, complete and selective production of αCCs at a low catalyst loading (2.5 mol %) under solvent‐free conditions. This study opens new avenues for the facile and selective synthesis of libraries of αCCs from CO2 and propargylic alcohol by using simple organocatalysts.

We have explored the domino reaction between propargylic alcohols, carbon dioxide, and various alcohols with the double objective to prepare oxo-alkyl carbonates with a high yield and selectivity under mild conditions and to extend the process to the synthesis of phosgene-free polycarbonates. We first searched for a common catalytic system that was highly selective for the two reactions involved in the domino process, i.e., the cycloaddition of CO 2 to propargylic alcohol to yield α-alkylidene cyclic carbonate (αCC) and the alcoholysis of αCC to furnish oxo-alkyl carbonate. Kinetics studies monitored by operando IR spectroscopy and supported by 1 H NMR analyses and DFT modeling have permitted us to identify an efficient binary catalytic system composed of a combination of tetrabutylammonium phenolate [TBA][OPh] and silver iodide (AgI) (or copper iodide (CuI)) and to understand its action mode. The [TBA][OPh]/ AgI catalytic system (5 mol %) was then successfully implemented for the selective preparation of a range of oxo-alkyl carbonates by the domino reaction with alcohols and propargylic alcohols of different structures. Most of these oxo-alkyl carbonates were produced at a high yield (≥97%) under mild operating conditions, i.e., at 60 °C and 1 bar of CO 2 . The one-pot synthesis of various poly(βoxo-carbonate)s from bis(propargylic alcohol)s, diols, and CO 2 was finally investigated, and the best operating conditions ([TBA][OPh]/AgI (10 mol %), 60 °C, 15 bar) afforded polycarbonate oligomers with weight-average molar masses of 4300 g/mol.Although the system should be optimized to produce longer polymer chains, this process offers a new phosgene-free alternative to the synthesis of functional polycarbonates poly(β-oxo-carbonate)s) under mild conditions.

A silver-catalyzed cascade conversion of modular alkyne-1,n-diols and carbon dioxide has been developed allowing for the selective formation of keto-functionalized cyclic carbonates. The protocol is characterized by its operational simplicity, excellent scope of carbonate-based heterocycles, and mild reaction conditions. In situ IR studies, control experiments, and detailed computational analysis of these manifolds reveal the intermediacy of an α-alkylidene carbonate that is intercepted by an intramolecular alcohol nucleophile. The synthetic potential of this conceptually attractive CO 2 transformation is demonstrated in the preparation of larger ring carbonates and their thermal rearrangement to sterically crowded, five-membered fused carbonate products.

Carbon dioxide is a renewable, inexhaustible, and cheap alternative to fossil resources for the production of fine chemicals and plastics. It can notably be converted into exovinylene cyclic carbonates, unique synthons gaining momentum for the preparation of an impressive range of important organic molecules and functional polymers, in reactions proceeding with 100 % atom economy under mild operating conditions in most cases. This Review summarizes the recent advances in their synthesis with particular attention on describing the catalysts needed for their preparation and discussing the unique reactivity of these CO2‐based heterocycles for the construction of diverse organic building blocks and (functional) polymers. We also discuss the challenges and the future perspectives in the field.