Atroposelective arene-forming alkene metathesis

Alkene metathesis catalysed by enantiopure metal alkylidene complexes enables versatile strategies to products with configurationally-defined stereocentres. Desymmetrisation processes thereby provide particularly reliable stereoselective routes to aliphatic structures, while the differentiation of aromatic stereogenic units remained an outstanding challenge. Herein, we describe the feasibility of alkene metathesis to catalytically control stereogenic axes by traceless arene formation. Stereodynamic trienes are selectively converted into corresponding binaphthalene atropisomers upon exposure to a chiral molybdenum catalyst. Remarkably, stereoselective arene-forming metathesis allows high yields and enantioselectivities of up to 98:2 e.r. As the disconnection of each bond of aromatic products is retrosynthetically conceivable, it is anticipated that forging arenes by means of stereoselective metathesis will enable versatile approaches for the synthesis of a broad range of molecular topologies with precisely defined configuration.