Design and Synthesis of Aromatics through [2+2+2] Cyclotrimerization

The [2+2+2] cycloaddition reaction is a useful tool to realize unusual chemical transformations which are not achievable by traditional methods. Here, we report our work during the past two decades that involve utilization of transition-metal complexes in a [2+2+2] cyclotrimerization reaction. Several key building blocks were assembled by a [2+2+2] cycloaddition approach and they have been further expanded by other synthetic transformations to design unusual amino acids and peptides, diphenylalkanes, bis-and trisaryl benzene derivatives, annulated benzocycloalkanes, spirocycles, and spirooxindole derivatives. Furthermore, we have also discussed about alkyne surrogates, environmentally friendly, and stereoselective [2+2+2] cycloaddition reactions. Application of the [2+2+2] cycloaddition reaction in total synthesis is also covered. In this review we also included others work to give a balanced view of the recent developments in the area of [2+2+2] cycloaddition.