Enantioselective construction of polychiral helical compounds via dynamic kinetic resolution
摘要
Chiral helicenes and their derivatives are valuable across diverse research fields, yet the development of helical chirality has lagged far behind that of point and axial chirality. The synthesis of polychiral or heteroatom-containing helical systems remains especially challenging because of limited starting materials and difficulties in stereochemical control. Here we computationally design a flexible oxa[4]helicenoid-ol scaffold with an optimal rotational barrier (ΔG‡ = 21.7 kcal mol−1) and enantioselective recognition ability, enabling dynamic kinetic resolution under mild conditions. This platform allows efficient access to helicenes bearing either dual helical chirality or combined helical and axial chirality, with excellent enantio-, diastereo- and E/Z selectivities. The strategy incorporates non-aromatic oxacycles, breaks conventional cyclization patterns and expands the structural diversity of helical chiral scaffolds. Density functional theory calculations elucidate the mechanistic origins of reactivity and stereoselectivity. The resulting helicenoid-quinones are readily derivatized and display promising optical properties for functional materials.