Ionic liquids have emerged as excellent solvents for synthesis and catalysis in the past decades due to their special properties. However, their relatively high cost and potential risks to human health and environment make their function as catalysts rather than solvents more popular. Incorporating specific functional group(s) into one or both ions of ionic liquids to make them catalytic is highly important. Numerous so-called task-specific or functionalized ionic liquids are designed and successfully applied in catalyzing various reactions. In this review, we present the latest achievements in the carbon-heteroatom bond formation reactions catalyzed by task-specific ionic liquids. The contents are arranged according to the specific types of carbon-heteroatom bond formation reactions. As for the type of task-specific ionic liquids, this review focuses on acidic ionic liquids, basic ionic liquids, organometallic ionic liquids, acid-base bifunctional ionic liquids and chiral ionic liquids. Contents
1 Introduction
2 Formation of carbon-oxygen bonds
2.1 Formation of esters
2.2 Formation of ethers
2.3 Protection of carbonyl and hydroxyl groups
2.4 Oxidation of olefins
2.5 Related carbonylation reactions
2.6 Synthesis of oxygen-containing heterocycles
3 Formation of carbon-nitrogen bonds
3.1 Formation of β-amino carbonyl compounds
3.2 Formation of amides
3.3 Formation of carbon-nitrogen double bonds
3.4 N-Alkylation reaction
3.5 Hydroamination reaction
3.6 Protection of amino groups
3.7 Nitration reaction
3.8 Asymmetric aza Diels-Alder reaction
3.9 Related carbonylation reactions
3.10 Synthesis of nitrogen-containing heterocycles
4 Formation of other carbon-heteroatom bonds
4.1 Formation of carbon-sulfur bonds
4.2 Formation of carbon-halogen bonds
5 Conclusion and outlook