Gold-Catalyzed Enantioselective Synthesis, Crystal Structure, and Photophysical/Chiroptical Properties of Aza[10]helicenes.

The enantioselective synthesis of an aza[10]helicene, possessing two pyridone units, has been achieved by the gold-catalyzed intramolecular quadruple hydroarylation of a tetrayne. This aza[10]helicene was successfully converted into a fully aromatic aza[10]helicene, possessing two pyridine units. Structure-photophysical and chiroptical properties relationship in a series of azahelicene isomers has also been disclosed.

Rh-Mediated Enantioselective Synthesis, Crystal Structures, and Photophysical/Chiroptical Properties of Phenanthrenol-Based [9]Helicene-like Molecules.

The enantioselective synthesis of phenanthrenol-based [9]helicene-like molecules has been achieved via the rhodium-mediated intramolecular [2 + 2 + 2] cycloadditions of 3-phenanthrenol-linked triynes. Crystal structures and photophysical/chiroptical properties of these [9]helicene-like molecules were compared with the corresponding [7]helicene-like molecules.

Rhodium-Catalyzed Atroposelective [2 + 2 + 2] Cycloaddition of Ortho-Substituted Phenyl Diynes with Nitriles: Effect of Ortho Substituents on Regio- and Enantioselectivity.

Axially chiral 3-(2-halophenyl)pyridines were successfully synthesized in high yields with excellent enantioselectivity by the cationic rhodium(I)/(S)-H8-BINAP complex-catalyzed atroposelective [2 + 2 + 2] cycloaddition of (o-halophenyl)diynes with nitriles. Interestingly, regio- and enantioselectivity highly depend on ortho substituents on the phenyl group of diynes. When the ortho substituents were methoxy and methoxycarbonyl groups, axially chiral 3-arylpyridines were obtained as a major product, while enantioselectivity was lowered significantly. On the other hand, when the ortho substituents were alkyl groups, regioselectivity was switched to give achiral 6-arylpyridines in high yields.

Rhodium(III)-Catalyzed Tandem [2+2+2] Annulation-Lactamization of Anilides with Two Alkynoates via Cleavage of Two Adjacent C-H or C-H/C-O bonds.

An electron-deficient Cp(E) rhodium(III) complex bearing a cyclopentadienyl ligand with two ethyl ester substituents catalyzes the tandem [2+2+2] annulation-lactamization of acetanilides with two alkynoates via cleavage of adjacent two C-H bonds to give densely substituted benzo[cd]indolones. The reactions of meta-methoxy-substituted acetanilides with two alkynoates also provided benzo[cd]indolones via cleavage of adjacent C-H/C-O bonds. Furthermore, 3,5-dimethoxyacetanilides reacted with two alkynoates to give dearomatized spiro compounds.