Tandem Reactions Based on the Cyclization of Carbon Dioxide and Propargylic Alcohols: Derivative Applications of α-Alkylidene Carbonates

As a well-known greenhouse gas, carbon dioxide (CO2) has attracted increasing levels of attention in areas of energy, environment, climate, etc. Notably, CO2 is an abundant, nonflammable, and renewable C1 feedstock in view of chemistry. Therefore, the transformation of CO2 into organic compounds is an extremely attractive research topic in modern green and sustainable chemistry. Among the numerous CO2 utilization methods, carboxylative cycloaddition of CO2 into propargylic alcohols is an ideal route due to the corresponding products, α-alkylidene cyclic carbonates, which are a series of highly functionalized compounds that supply numerous potential methods for the construction of various synthetically and biologically valuable agents. This cyclization reaction has been intensively studied and systematically summarized, in the past years. Therefore, attention has been gradually transferred to produce more derivative compounds. Herein, the tandem reactions of this cyclization with hydration, amination, alcoholysis, and isomerization to synthesize α-hydroxyl ketones, oxazolidinones, carbamates, unsymmetrical carbonates, tetronic acids, ethylene carbonates, etc. were systematically reviewed.

Hypercrosslinked Ionic Polymers with High Ionic Content for Efficient Conversion of Carbon Dioxide into Cyclic Carbonates

The effective conversion of carbon dioxide (CO2) into cyclic carbonates requires porous materials with high ionic content and large specific surface area. Herein, we developed a new systematic post-synthetic modification strategy for synthesizing imidazolium-based hypercrosslinked ionic polymers (HIPs) with high ionic content (up to 2.1 mmol g−1) and large specific surface area (385 m2 g−1) from porous hypercrosslinked polymers (HCPs) through addition reaction and quaternization. The obtained HIPs were efficient in CO2 capture and conversion. Under the synergistic effect of high ionic content, large specific surface area, and plentiful micro/mesoporosity, the metal-free catalyst [HCP-CH2-Im][Cl]-1 exhibited quantitative selectivities, high catalytic yields, and good substrate compatibility for the conversion of CO2 into cyclic carbonates at atmospheric pressure (0.1 MPa) in a shorter reaction time in the absence of cocatalysts, solvents, and additives. High catalytic yields (styrene oxide, 120 °C, 8 h, 94% yield; 100 °C, 20 h, 93% yield) can be achieved by appropriately extending the reaction times at low temperature, and the reaction times are shorter than other porous materials under the same conditions. This work provides a new strategy for synthesizing an efficient metal-free heterogeneous catalyst with high ionic content and a large specific surface area from HCPs for the conversion of CO2 into cyclic carbonates. It also demonstrates that the ionic content and specific surface area must be coordinated to obtain high catalytic activity for CO2 cycloaddition reaction.

Halide-free catalytic carbon dioxide fixation of epoxides to cyclic carbonates under atmospheric pressure

Epoxides to cyclic carbonates conversion utilizing CO2 is one of the efficient approaches for CO2 fixation. Atmospheric fixation of CO2 generally required the use of halogen containing catalysts or additionally...

Regio- and enantioselective formation of tetrazole-bearing quaternary stereocenters via palladium-catalyzed allylic amination

Based on palladium-catalyzed allylic amination reaction, the first general example of enantioselective formation of tetrazole-bearing quaternary stereocenter has been developed. The protocol utilizes ambivalent tetrazole and vinyl cyclic carbonates as...

Guanidyl-implanted UiO-66 as efficient catalysts for enhanced conversion of carbon dioxide into cyclic carbonates

The development of heterogeneous catalysts for promoting epoxide cycloaddition with carbon dioxide is highly desirable for recycling CO2 and achieving the goal of carbon neutrality. Herein, we designed and synthesized...

Fabrication of a hollow sphere N, S co-doped bifunctional carbon catalyst for sustainable fixation of CO2 to cyclic carbonates

Execution of compositional doping by more than one element simultaneously inside carbon matrix is a challenging task for designing advanced carbon-based materials and nanotechnology. Herein, we have integrated a template-free...