Tetra-ortho-substituted Axially Chiral Biaryls via [2+2+2] Cycloadditions

Significance

Complex axially chiral biaryls can be prepared in one step from two acyclic starting materials. Besides this method, very few methods allow the preparation of tetra-ortho-substituted biaryl compounds. With the double [2+2+2] cyclo­addition, in most cases the mono-annulated products 7 are observed and can be resubjected to a second cycloaddition to obtain non-symmetrically substituted biaryl compounds 8 with high enan­tioselectivity.