Salen‐Complex‐Mediated Formation of Cyclic Carbonates by Cycloaddition of CO<sub>2</sub> to Epoxides

Decortes, Antonello; Castilla, Ana M.; Kleij, Arjan W.

doi:10.1002/anie.201002087

Cited by 770 publications

(322 citation statements)

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“…Therefore, the nucleophile can be embedded or weakly coordinated to the catalyst resulting a in a dual effect: it can act as a nucleophile in the ring-opening of the epoxide and/or favor the coordination of the oxirane to the metal center by a trans ligand effect. 13 Salen and salphen catalysts are characterized by an easy preparation, allowing for large-scale synthesis and potential commercial applications. They can also be fine-tuned from a reactivity point of view, by ad hoc structure modifications; the possibility of direct inclusion of a nucleophilic co-catalyst, variation in the type of active metal center, and formation of mono-and multinuclear catalysts.…”

Section: Development Of Improved Reactivity In Coc Synthesismentioning

confidence: 99%

“…1,2,6 Despite the disadvantage of CO 2 having sluggish reactivity, recent work has unambiguously demonstrated that new opportunities may become available when proper catalytic methods are designed that help to improve the reactivity, selectivity and/or sustainability profiles of such processes. Among the most widely studied reactions in CO 2 catalysis is the formation of cyclic organic carbonates (COCs) [11][12][13][14][15][16][17][18] apart from their analogous and related linear carbonates 19 and poly(carbonates). [20][21][22] These COCs have been frequently associated with numerous applications involving them as non-protic solvents, precursors for poly(carbonate) synthesis, electrolyte solvents and more recently as useful intermediates in organic synthesis.…”

Section: Introductionmentioning

confidence: 99%

“…As will be highlighted throughout the text, homogenous metal catalysts for efficient oxirane/CO 2 coupling reactions include mono-and bi-metallic species as well as bifunctional systems that embed both the Lewis acid and the nucleophile within a single molecular entity. 13,17 In this review article we wish to highlight the most recent developments in the field of catalytic cyclic organic carbonate (COC) synthesis with a primary focus on those contributions that have helped to amplify the field of COCs having potential towards organic synthetic applications. Attention will therefore be given to the catalytic processes that have disclosed new reactivity patterns, improved activity profiles and unusual selectivity.…”

Section: Introductionmentioning

confidence: 99%

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Recent Advances in the Catalytic Preparation of Cyclic Organic Carbonates

2015

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ABSTRACT:The catalytic formation of cyclic organic carbonates (COCs) using carbon dioxide (CO 2 ) as a renewable carbon feed stock is a highly vibrant area of research with an increasing amount of researchers focusing on this thematic investigation. These organic carbonates are highly useful building blocks and nontoxic reagents, and are most commonly derived from CO 2 coupling reactions with oxirane and di-alcohol precursors using homogeneous catalysis methodologies. The activation of suitable reaction partners using catalysis as a key technology is a requisite for efficient CO 2 conversion as its high kinetic stability poses a barrier to access functional organic molecules with added value in both academic and industrial laboratories. Though this area of science has been flourishing for at least a decade, in the last 2−3 years significant advancements have been made to address the general reactivity and selectivity issues that are associated with the formation of COCs. Here we present a concise overview of these activities with a primary focus to highlight the most important progress made and the opportunities that catalysis can bring about when the synthesis of these intermediates is optimized to a higher level of sophistication. The attention will be limited to those cases where homogeneous metal-containing systems have been employed as they possess the highest potential for directed organic synthesis using CO 2 as molecular building block. This review discusses examples of exceptional reactivity and selectivity taking into account the challenging nature of the substrates that were involved, and mechanistic understanding guiding the optimization of these protocols is also highlighted.

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Section: Development Of Improved Reactivity In Coc Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Recent Advances in the Catalytic Preparation of Cyclic Organic Carbonates

2015

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“…[142][143][144][145] One of the most successful classes of catalysts are cobalt, chromium and aluminium salen complexes, which have also allowed the development of asymmetric variations of the reaction. [146] The reaction with cumulenes is not limited to CO2. In particular, isocyanates, isothiocyanates and carbodiimides react with epoxides to give the corresponding five-membered heterocycles.…”

Section: Formal [3+2] Cycloadditions With Cumulenesmentioning

confidence: 99%

Synthesis of Saturated Heterocycles via Metal-Catalyzed Formal Cycloaddition Reactions That Generate a C–N or C–O Bond

Waser

2013

Topics in Heterocyclic Chemistry

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In this section, the synthesis of saturated N-and O-heterocycles via formal cycloaddition is presented. The main focus is on metal-catalyzed reactions involving C-C or C-X  bond cleavage in three-or four-membered rings. After a fast presentation of pioneering works, the important breakthroughs of the last two decades are presented. The section starts with reactions involving three-membered rings. Formal [3+2] cycloadditions of donor-acceptor-substituted cyclopropanes and methylenecyclopropanes with carbonyls and imines are important methods to access tetrahydrofuran and pyrrolidine heterocycles. Formal [3+3] cycloadditions have emerged more recently. On the other hand, reactions of epoxides and aziridines with carbon monoxide or cumulenes are now well-established method to access heterocycles. These processes have been completed more recently with cycloaddition with olefins, carbonyls and imines. The section ends with the emerging field of four-membered ring activation for cycloaddition with  systems. This is the peer reviewed version of the following article: Top. Heterocycl. Chem. 2013, 32, 225, which The discovery of classical cycloaddition reactions, such as the (hetero) DielsAlder and 1,3-dipolar cycloadditions, has contributed tremendously to a more efficient access towards both carbocycles and heterocycles. The introduction of the term cycloaddition was necessary to distinguish these new types of reactions from previously discovered processes leading to cyclic structures, such as the famous Robinson annulation. In principle, each cycloaddition can be considered as a special case of the more general annulation process, but from which point on an annulation can be called a cycloaddition has been the topic of intensive discussions for decades, and is still not settled today. In 1968, Huisgen proposed a set of rules for the definition of cycloaddition, and the two first are still largely recognized as prerequisite: Although the rule that all the atoms of the starting materials have to be included in the product is not explicitly included in the definition, this requirement is usually recognized by most organic chemists. Even if electrocyclic cyclization processes were included in the original definition of Huisgen, the term cycloaddition is mostly used today for those reactions proceeding via the formation of at least two new bonds. Nevertheless, several researchers think that the term cycloaddition should be more strictly limited to reactions involving a continuous overlap of  electrons, and consequently allowing a concerted process. In fact, in his seminal publication, Huisgen already introduced further rules, in particular rule number 3, which explicitly stated that cycloadditions should not involve the cleavage of sigma bonds: -Huisgen Rule 3: "Cycloadditions do not involve the cleavage of  bonds." Unfortunately, in the same publication, Huisgen also described several reactions proceeding via -bond cleavage as cycloaddition. To solve this definition dilemma, several researchers have used th...

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“…Therefore, chemical fixation of CO2 has been a hot topic from the viewpoint of sustainable development and green chemistry. In this regard, one of the most promising strategies is the transformation of CO2 with epoxides to yield the corresponding cyclic carbonates (Scheme 1) [3], which is considered green because of 100% atom efficiency. Also cyclic carbonates can be widely applied in proton inert solvents, as precursors for polycarbonates and polyurethanes synthesis, as electrolytes in lithium secondary batteries, and as intermediates for production of pharmaceuticals, fine chemicals and agricultural chemicals [4,5].…”

Section: Introductionmentioning

confidence: 99%

Guanidine Hydrochloride/ZnI2 as Heterogeneous Catalyst for Conversion of CO2 and Epoxides to Cyclic Carbonates under Mild Conditions

Liu

Liang

et al. 2015

Catalysts

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Abstract:In this article, the combination of guanidine hydrochloride with co-catalyst ZnI2 proved to be a highly efficient heterogeneous catalyst for the environmentally benign, solvent-free synthesis of cyclic carbonates under mild reaction conditions. The effects of different co-catalysts as well as reaction parameters including catalyst loadings, CO2 pressure, reaction temperature, and reaction time on the coupling reaction of CO2 to propylene oxide were thoroughly investigated. With the molar ratio of guanidine hydrochloride to ZnI2 at 5:1, excellent yield (94%) and selectivity (≥99%) of propylene carbonate were obtained under 100 °C and at 1 MPa for 1.5 h. Additionally, ZnI2 could be recycled, but because of the washing loss of guanidine hydrochloride, there was a slight decrease in the yield of propylene carbonate. Gratifyingly, the activity of the catalytic system could be restored by adding additional 20 mol% of fresh guanidine hydrochloride, thus exhibiting excellent recyclability of the ZnI2 catalyst. Moreover, the binary catalysts were also versatile when using other epoxides for CO2 cycloaddition. A possible reaction mechanism was proposed wherein guanidine hydrochloride plays a dual role in activating OPEN ACCESS Catalysts 2015, 5 120 CO2 and epoxide, and ZnI2 activated epoxide, simultaneously. The synergistic effect of guanidine hydrochloride and ZnI2 ensure the reaction proceeds effectively.

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Salen‐Complex‐Mediated Formation of Cyclic Carbonates by Cycloaddition of CO₂ to Epoxides

Cited by 770 publications

References 84 publications

Recent Advances in the Catalytic Preparation of Cyclic Organic Carbonates

Recent Advances in the Catalytic Preparation of Cyclic Organic Carbonates

Synthesis of Saturated Heterocycles via Metal-Catalyzed Formal Cycloaddition Reactions That Generate a C–N or C–O Bond

Guanidine Hydrochloride/ZnI2 as Heterogeneous Catalyst for Conversion of CO2 and Epoxides to Cyclic Carbonates under Mild Conditions

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Salen‐Complex‐Mediated Formation of Cyclic Carbonates by Cycloaddition of CO2 to Epoxides

Cited by 770 publications

References 84 publications

Recent Advances in the Catalytic Preparation of Cyclic Organic Carbonates

Recent Advances in the Catalytic Preparation of Cyclic Organic Carbonates

Synthesis of Saturated Heterocycles via Metal-Catalyzed Formal Cycloaddition Reactions That Generate a C–N or C–O Bond

Guanidine Hydrochloride/ZnI2 as Heterogeneous Catalyst for Conversion of CO2 and Epoxides to Cyclic Carbonates under Mild Conditions

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Product

Resources

About

Salen‐Complex‐Mediated Formation of Cyclic Carbonates by Cycloaddition of CO₂ to Epoxides