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

Abstract

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. 1 Introduction 2 Unusual Amino Acids and Peptides 3 Heteroanalogues of Indane 4 Diphenylalkane Derivatives 5 Multi-Armed Aryl Benzene Derivatives 6 Annulated Benzocycloalkanes 7 Spirocycles 8 Selectivity in [2+2+2] Cycloaddition of Alkynes 9 [2+2+2] Cycloaddition Reactions under Environmentally Friendly Conditions 10 Alkyne Surrogates 11 Domino Reactions involving a [2+2+2] Cycloaddition 12 Biologically Important Targets/Total Synthesis 13 Conclusions.