## 3 Potential Applications in Biological Studies
### Heterocyclic Compounds  
Heterocyclic systems represent the most general structural unit of many natural compounds; they have valuable biologically properties and a wide range of applications in the pharmaceutical industry [123,124]. Oxa- and aza-heterocycles atoms are the most representative, which have been used to access new compounds in chemical industries [125]. In the following sections, we mention studies from recent years that have shown efficient synthetic methodologies for the functionalization of heterocycles via the insertion of different substituents in the chemical structure. The oxazolidin-2-ones **62** were prepared through the reaction between cyclic carbonates **1** and aryl amines **63** in the presence of 1-butyl-3-methylimidazol acetate ([bmim]OAc) as an eco-efficient catalyst (Scheme 51) [126]. NMR spectroscopy and DFT calculations demonstrated that both the anion and the cation of the ionic liquid catalyst cooperatively activate the starting materials via formation of hydrogen bonds. Thus, several compounds **62** were obtained with good to excellent yields after 9 h at 130 \({}^{\circ}\)C. Ethylene-, propylene-, and 4-phenoxyylethylylene carbonates **1** were reacted with a range of arylamines **63**. The carbonylation reaction using different cyclic carbonates showed that steric hindrance negatively influenced the reactivity in the following order: ethylene carbonate \(>\) propylene carbonate \(>\) 4-phenoxyylethylylene carbonate. In the same work, a [bmim]OAc-catalyzed synthesis approach for aryl bis-oxazolidin-2-ones **97** from cyclic carbonates **1** and aryl- or heteroaryldiamines **98** was devised. Ethylene- and propylene carbonate smoothly reacted with aromatic diamines to form the corresponding bis-oxazolidin-2-ones **97** in good yields (Scheme 52). In addition, the imidazolium-based ionic liquids also exhibited high catalytic activity to prepare 3-aryl-[1,3]-oxazinan-2-ones from trimethylene carbonate and [1,3]-dithiolan-2-ylidene-arylamines from ethylene trithiocarbonate [126]. Due to the versatility of glycerol carbonates, several investigations have been conducted, aiming to develop protocols for the introduction of the GC unit in heterocyclic systems. In 2012, [PERSON] and co-workers [127] reported the functionalization of 1-phenyl-1\(H\)-pyrazol-3-ol **99** with TGC **1h**. The synthesis of phenylpyrazole derivatives has attracted the attention of synthetic organic chemists because of their broad spectrum of biological activities. In this protocol, **1h** reacts with compound **99** in DMF at room temperature in the presence of K\({}_{2}\)CO\({}_{3}\) to provide chemoselectively for 4-[[(1-phenyl-1\(H\)-pyrazol-3-yl)oxy]methyl]-1,3-dioxolan-2-one **100** with 71% yield (Scheme 53). The same group [14] reported the use of **1h** as a bis-electrophile for the \(N\)-glycerol functionalization of diverse aza-aromatic systems **101-106** (Scheme 54). The ambident benzimidazole **101** was converted into the carbonate **107** with 76% yield after 5 h, whereas under the same conditions, benzotriazole **102** provided a mixture of 1- and 2-substituted regioisomers (85% global yield). For less acidic aza-heterocyclic systems, a decrease in the yield was observed, e.g., 1\(H\)-indole **108** led to the \(N\)-alkylated compound **109** with only 34% yield. Comparatively, methyl 1\(H\)-indole-3-carboxylate **104**, with the \(N\)-H bond under the influence of the electron-withdrawing group, was more reactive than unsubstituted indoles, providing the expected product with 48% yield. Carbazole **105** reacted in a solvent-dependent way to provides mixtures with 60% yield for \(N\)-alkylated product **110** and the isomeric glycidyl carbamate. When reacting 1,2,3,4-tetrahydrocyclopent[\(b\)]indole as the substrate in DMF, the corresponding glycidyl carbamate was obtained exclusively with 51% yield. Various chemistshave evaluated the performance of benzimidazole-derived carbonates as building blocks for useful transformations.