## 2 Applications in Chemistry
### Decarboxylation of Cyclic Carbonates
In ultrasonic activation, RT-10 CoZn showed 100% selectivity for **2a**, whereas in microwave activation, RT-10 CoZn reaches 71% conversion yield to **2a** with total selectivity, indicating that this catalyst delivers the best performance in the shortest reaction time (30 min vs. 6-7 h under ultrasonic activation and 23 h under thermal activation). The hypothetical mechanism is based on the polymerization of **1a** to poly-(glycerol-1,2-carbonate), which then forms **2a** through CO\({}_{2}\) release. The reuse of both heterogeneous catalysts was not mentioned. [PERSON] and co-workers [28] studied the use of a binary zinc-lanthanum catalytic system (ZnO/La\({}_{2}\)O\({}_{3}\); Zn:La ratio = 1:9) in the decarboxylative process. When 10 wt% of the mixed oxides was employed in the reaction, **2a** was obtained with 76% yield after 2 h reaction under reduced pressure (0.05 MPa) in a nonspecific solvent below 180 \({}^{\circ}\)C (Scheme 2). The evaluation of the catalytic activity showed that an increase in the La molar ratio correlates with a yield increase of **2a**, due to equilibrium between acidic and basic sites on the surface of the catalyst. However, when the reaction was performed in the presence of La\({}_{2}\)O\({}_{3}\) alone, **2a** was obtained with 47% yield only. [PERSON] and co-workers [29] produced **2a** by using the same ZnO/La\({}_{2}\)O\({}_{3}\) system, albeit with a molar ratio for Zn/La of 4:1. In this work, the performance of the catalyst was studied up to four re-uses (about 64-97% conversion) and a decrease of activity was noted after each cycle, because of the adsorption of carbonaceous side products on the catalytic basic sites. This problem was minimized by calcination of the catalyst to restore its activity. As the major objective of the authors was to synthesize **1a** by dimethyl carbonate transesterification with glycerol, no additional studies were carried out to increase the catalyst's activity in preparing **2a**. [PERSON] and co-workers [30] described a one-pot consecutive glycidol synthesis method from glycerol, whereby carbonylation of glycerol **3a** with urea first takes place under high pressure using a homogeneous zinc catalyst to produce GC **1a**. Subsequently, decarboxylation is used to obtain the desired **2a** product (Scheme 3). This second reaction proceeds in acetonitrile in the presence of zinc acetate to give glycidol **2a** with 67% yield after 1.5 h. According to the authors, the high catalytic activity of Zn(OAc)\({}_{2}\) can be attributed to the formation of the intermediate species [Zn(NH\({}_{3}\))\({}_{\bullet}\)(OAc)\({}_{2}\)]. An original decarboxylation process involving GC **1** was described by [PERSON] and co-workers [31] through an organocatalytic coupling reaction between the bromolactide **4** and carbonates **1**, in the presence of the heterocyclic carbene 1,3-bis(2,4,6-trimethylphenyl)imidazol-zol-2-ylidene (IMes), resulting in the formation of chiral keto-diesters **5** (Scheme 4). The reaction was found to proceed at 100 \({}^{\circ}\)C in times ranging from 13 h to 15 h, delivering the desired products in high yields (72-93%). More recently, the use of palladium catalysis for the decarboxylation of GC **1a** was reported [32; 33]. [PERSON] and co-workers [32] described the synthesis of ethers via a Pd-catalyzed reaction of carbonates **6** with phenols **7** in THF in the presence of cesium carbonate (Cs\({}_{2}\)CO\({}_{3}\)) and phosphoramidite or phosphine ligands (Scheme 5). The authors observed that the choice of the ligand influences the regioselectivity of the reaction. Thus, by changing the ligands it was possible to direct the reaction to prepare either branched- **8** or linear allylic aryl ethers **8**. Reacting the cyclic carbonates at 0 \({}^{\circ}\)C for 36 h led to aryl ethers **8**, while running the same reaction at room temperature for 12 h mainly provided **9**. The products were obtained in moderate to excellent yields (49-98%) and with considerable enantio-induction.