Jaroslav Vacek

Despite recent tremendous progress in the synthesis of nonplanar chiral aromatics, and helicenes in particular, their conversion to half‐sandwich or sandwich transition metal complexes still lags behind, although they represent an attractive family of modular and underexplored chiral architectures with a potential catalytic use. In this work, starting from various chiral helicene‐indene proligands, we prepared the enantio‐ and diastereopure oxa[6]‐ and oxa[7]helicene‐indenido half‐sandwich Rh^I and Rh^III complexes and oxa[7]helicene‐bisindenido ansa‐metallocene Fe^II complex. To document their use, oxahelicene‐indenido half‐sandwich Rh^III complexes were employed as chiral catalysts in enantioselective C−H arylation of benzo[h]quinolines with 1‐diazonaphthoquinones to afford a series of axially chiral biaryls in mostly good to high yields and in up to 96 : 4 er. Thus, we developed stereocontrolled synthesis of chiral helicene‐indenido ansa‐ and half‐sandwich metal complexes, successfully demonstrated the first use of such helicene Cp‐related metal complexes in enantioselective catalysis, and described an unusual sequence of efficient central‐to‐helical‐to‐planar‐to‐axial chirality transfer.

Despite recent tremendous progress in the synthesis of nonplanar chiral aromatics, and helicenes in particular, their conversion to half‐sandwich or sandwich transition metal complexes still lags behind, although they represent an attractive family of modular and underexplored chiral architectures with a potential catalytic use. In this work, starting from various chiral helicene‐indene proligands, we prepared the enantio‐ and diastereopure oxa[6]‐ and oxa[7]helicene‐indenido half‐sandwich Rh^I and Rh^III complexes and oxa[7]helicene‐bisindenido ansa‐metallocene Fe^II complex. To document their use, oxahelicene‐indenido half‐sandwich Rh^III complexes were employed as chiral catalysts in enantioselective C−H arylation of benzo[h]quinolines with 1‐diazonaphthoquinones to afford a series of axially chiral biaryls in mostly good to high yields and in up to 96 : 4 er. Thus, we developed stereocontrolled synthesis of chiral helicene‐indenido ansa‐ and half‐sandwich metal complexes, successfully demonstrated the first use of such helicene Cp‐related metal complexes in enantioselective catalysis, and described an unusual sequence of efficient central‐to‐helical‐to‐planar‐to‐axial chirality transfer.

Water splitting using polymer photocatalysts is a key technology to a truly sustainable hydrogen‐based energy economy. Synthetic chemists have intuitively tried to enhance photocatalytic activity by tuning the length of π‐conjugated domains of their semiconducting polymers, but the increasing flexibility and hydrophobicity of ever‐larger organic building blocks leads to adverse effects such as structural collapse and inaccessible catalytic sites. To reach the ideal optical band gap of about 2.3 eV, A library of eight sulfur and nitrogen containing porous polymers (SNPs) with similar geometries but with optical band gaps ranging from 2.07 to 2.60 eV was synthesized using Stille coupling. These polymers combine π‐conjugated electron‐withdrawing triazine (C₃N₃) and electron donating, sulfur‐containing moieties as covalently bonded donor–acceptor frameworks with permanent porosity. The remarkable optical properties of SNPs enable fluorescence on‐off sensing of volatile organic compounds and illustrate intrinsic charge‐transfer effects.