CO2 as a Building Block in Organic Synthesis

Shoubhik Das

• Publisher: Wiley-VCH
• Year: 2020
• ISBN:
  9783527821969
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Physical & Theoretical Chemistry

A guide to the fascinating application of CO 2 as a building block in organic synthesis

This important book explores modern organic synthesis'use of the cheap, non-toxic and abundant chemical CO 2 as an attractive C1 building block. With contributions from an international panel of experts, CO 2 as a Building Block in Organic Synthesis offers a review of the most important reactions which use CO 2 as a building block in organic synthesis.

The contributors examine a wide-range of CO 2 reactions including methylation reactions, CH bond functionalization, carboxylation, cyclic carbonate synthesis, multicomponent reactions, and many more. The book reviews the most recent developments in the field and also:

• Presents the most important reactions like CH-bond functionalization, carboxylation, carbonate synthesis and many more
• Contains contributions from an international panel of experts
• Offers a comprehensive resource for academics and professionals in the field

Written for organic chemists, chemists working with or on organometallics, catalytic chemists, pharmaceutical chemists, and chemists in industry, CO 2 as Building Block in Organic Synthesis contains an analysis of the most important reactions which use CO 2 as an effective building block in organic synthesis.

1
Photochemical and Substrate‐Driven CO ₂ Conversion

Bart Limburg¹, Cristina Maquilón^1,2, and Arjan W. Kleij^1,3

¹Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans 16, 43007, Tarragona, Spain

²Universitat Rovira i Virgili, Departament de Química Física i Inorgànica, Marcel·lí Domingo s/n, 43007, Tarragona, Spain

³Catalan Institute of Research and Advanced Studies (ICREA), Pg. Lluis Companys 23, 08010, Barcelona, Spain

1.1 Introduction

The use of carbon dioxide (CO₂) as a raw material in molecular science has been the subject of many investigations. Obviously, the replacement of fossil fuel‐based chemistries with those primarily based on CO₂ cannot alleviate the challenges we are facing in terms of global carbon emissions and managing the carbon cycle. However, new technologies that can help to partially replace the nonsustainable feedstock into renewable and widely available ones will help to transition to a circular rather than a linear economy [1]. In this regard, technologies encompassing the use of catalysts have demonstrated that the valorization of CO₂ is feasible, offering many opportunities in the areas of organic [2–5], polymer [6–8], and fuel‐based chemistries [9, 10].

The use of CO₂ as a reagent in nonreductive coupling reactions (i.e. after integrating the CO₂ molecule into an organic substrate, the oxidation state of the carbon center, +4, remains unchanged) has been prominent in the wider area of CO₂ catalysis. In this respect, the [3 + 2] cycloaddition reaction of CO₂ and epoxides [11–15], and to a minor extent oxetanes [16, 17], has been among the most widely studied transformations. Conventionally, the formation of cyclic carbonates is carried out using phosgene as a reagent (Figure 1.1a), and obviously, finding more sustainable alternative routes has been the subject of intense studies over the past 20 years. Substantial progress has been noted in the synthesis of cyclic carbonates and the required catalysts for these [3 + 2] cycloaddition reactions, and nowadays, a variety of epoxides including terminal [18–20] and the more challenging internal ones with multiple substituents can be readily utilized (Figure 1.1b) [21–28]. Notwithstanding, there are still important issues to resolve in order to further advance the sustainability of these kinds of nonreductive CO₂ conversions in terms of reaction conditions (preferably using ambient conditions) [29, 30], catalyst structures (preferably halide‐free ones) [31], and expansion of the portfolio of cyclic carbonate compounds by using conceptually different approaches [32, 33].

Recently, various halide‐free methodologies have been reported (Figure 1.1c) [31,34–40], which are important to reduce both operational cost and corrosion issues where typical binary catalyst systems (i.e. a combination of a Lewis acidic complex and a halide additive) are used. For instance, North and coworkers used a bimetallic, O‐bridged Al(III)salen complex that is able to induce insertion of CO₂ into one of the Al─O bonds, thereby forming an Al‐ carbonate intermediate [34]. This nucleophilic species further engages with the epoxide substrate to induce ring opening to eventually give the cyclic carbonate product essentially in the absence of any cocatalytic halide. In a more recent contribution, the same authors reported the use of a bis‐phenol‐type salen organocatalyst that is able to induce formation of cyclic carbonates from terminal epoxides and CO₂, albeit at rather elevated reaction temperatures [35]. This work nicely builds on previous success in this area using multiphenolic (binary) organocatalysts as effective systems for cyclic carbonates derived from internal and terminal epoxides [41, 42]. Replacing salen diphenol with other types of H‐bond activators such as a combination of DBU/L‐histidine (DBU = 1,8‐diazabicyclo[5.4.0]undec‐7‐ene) also enables a halide‐free synthesis of these CO₂‐based heterocycles [36]. The design of other halide‐free systems (with this particular design characteristic although still in its early stage) clearly demonstrates a shift toward the use of more sustainable catalysts in the valorization of CO₂ into cyclic carbonates.

What should be the next step in the development of efficient catalysts for cyclic carbonate products (Figure 1.1d)? The recent literature testifies that the use of cyclic carbonates and related precursors to build more complex molecules [43–45] can only be carried out if the former can be prepared with a ce...

Table of contents

• Cover
• Table of Contents
• 1 Photochemical and Substrate‐Driven CO 2 Conversion
• 2 C–H Carboxylations with CO 2
• 3 Transition‐Metal‐Catalyzed C–H Carboxylation
• 4 Fixation of CO2 in Organic Molecules with Heterogeneous Catalysts
• 5 CO 2 Fixation into Organic Molecules via Carbon–Heteroatom Bond Formation
• 6 Carbonyl‐Ene Reactions of Alkenes with Carbon Dioxide
• 7 Recent Advances in Electrochemical Carboxylation of Organic Compounds for CO2 Valorization
• 8 Photocatalysis as a Powerful Tool for the Utilization of CO2 in Organic Synthesis
• 9 Direct Carboxylation of Alkenes and Alkynes
• 10 Homogeneous Iron Catalysts for the Synthesis of Useful Molecules from CO2
• 11 NHC‐catalyzed CO 2 Fixations in Organic Synthesis
• 12 Silver‐Catalyzed CO2 Fixation
• Index
• End User License Agreement