Lucía Álvarez‐Miguel

The synthesis of bio‐derived cyclic carbonates is attracting a lot of attention as the incorporation of bio‐derived functionality into these compounds provides the opportunity to prepare previously unknown structures, whilst also improving their sustainability profiles. This study presents a facile preparation of diastereomerically pure bio‐derived cyclic carbonates displaying a range of optical rotation values. These compounds are obtained from glycidol, amino acids and CO 2 in a facile two‐step approach. Initially, the diastereomerically pure amino acid functionalised epoxides are prepared through a robust Steglich esterification of enantiopure glycidol ( R or S ) and an amino acid ( D or L ). Thereafter, in a second step, cycloaddition of the epoxide with CO 2 results in the retention of the initial stereochemistry of the epoxide, furnishing novel diastereomerically pure and optically active cyclic carbonate products. A DFT study has explained the basis of this observed retention of configuration for these compounds. Further, results from this DFT study also provide new mechanistic information concerning a co‐catalyst‐free cycloaddition reaction starting from glycidol when using the gallium‐catalyst, which is found to operate through metal‐ligand cooperativity.

Three neutral Cu(I) complexes bearing 2,6‐dimethylphenyl isocyanide (CNXyl) and different triatomic pseudohalogens (SCN − , OCN − and N 3 − ) as ligands were efficiently synthesized and characterized. The solid‐state structures were unambiguously determined through single‐crystal X‐ray diffraction, revealing unexpected bridging coordination modes in the case of OCN − and N 3 − . All the complexes were tested for azide‐alkyne cycloaddition (CuAAC), showing interesting catalytic activity towards the formation of 1,4‐disubstituted‐1,2,3‐triazoles for the cyanato and the azido Cu(I) complexes. Both species afforded yields above 90% with 0.5 mol% of catalyst at 50°C for 24 h. Several alkynes and azides were tested using the more active azido Cu(I) complex, affording the corresponding triazoles in high yields. The azido Cu(I) complex also induced the intramolecular CuAAC in the presence of dimethyl acetylenedicarboxylate and benzyl bromide/phenylacetylene.