Catalytic Generation of Pyridyl Radicals via Electron Donor-Acceptor Complex Photoexcitation: Synthesis of 2-Pyridylindole-Based Heterobiaryls.

We report the catalytic generation of pyridyl radicals through photoexcitation of the electron donor-acceptor (EDA) complex, which enables the C2-selective heteroarylation of indole under ambient conditions. In this manifold, catalytic triarylamine and chloropyridine aggregate into an EDA complex in the presence of an inorganic base, making readily available chloropyridines good precursors for the generation of diverse pyridyl radicals. Given the broad reaction scope, this catalytic EDA complex protocol provides robust access to heterobiaryl scaffolds that are widely present in biologically important molecules.

Chiral Derivatives of 2-Aminotribenzotriquinacene: Synthesis and Optical Resolution.

Starting from a hitherto unknown 2-aminotribenzotriquinacene, several 2-amino-3-X-substituted TBTQ derivatives, all bearing a single -difunctionalized indane wing, were synthesized as rigid and chiral building blocks for the potential construction of complex supramolecular architectures. Efficient access to two pairs of enantiomeric TBTQ derivatives, namely, the peripheral -nitroaniline (X = NO) and the related anthranilic acid (X = COH), was developed using chiral auxiliaries as the resolving reagents. The structure of the intermediate diastereomers was confirmed by H and C NMR spectroscopy, high-resolution mass spectroscopy (HRMS), and polarimetry.

Trifluoroacetic Anhydride Promoted Copper(I)-Catalyzed Interrupted Click Reaction: From 1,2,3-Triazoles to 3-Trifluoromethyl-Substituted 1,2,4-Triazinones.

A copper(I)-catalyzed interrupted click reaction in the presence of trifluoroacetic anhydride has been developed, wherein an N-trifluoroacetyl group is used to accelerate the ring-opening of the putative 5-copper(I) triazolide intermediate. Under the optimized reaction conditions, a broad range of azides and alkynes were found to participate in this transformation, thus affording 3-trifluoromethyl-substituted 1,2,4-triazinones in moderate to excellent yields. The reaction has proven to be compatible with a variety of electron-withdrawing and electron-donating groups, halogens, and nitrogen- and sulfur-containing heterocycles, as well as pharmaceutically relevant molecules.