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
Key words
[2+2+2] cyclotrimerization - Diels–Alder - sultine - amino acids and peptides - spirocycles
- Wilkinson’s catalyst - Vollhardt’s catalyst - alkyne surrogates
