Photoredox-Catalyzed C-Indolyl/Quinolyl Glycosylation from 2-Styrylisocyanides and Glycosyl Bromides

Indole and quinoline structures are present in numerous biologically active molecules, making the synthesis of their glycosylation products a subject of extensive research and interest in drug development. Here, we report a photoredox strategy for the synthesis of C-indolyl and C-quinolyl glycosides using 2-styrylisocyanides and glycosyl bromides as building blocks. This approach offers mild reaction conditions, high α-selectivity, and scalability for large-scale reactions. The radical cyclization mode switching from 5-exo-trig to 6-endo-trig is achieved by selecting the substituents on the 2-vinyl group. This strategy enriches the toolbox of heterocyclic glycosylation methods and benefits advances in research on heteroaryl-based pharmaceuticals.

Investigating the structural chemistry of organotin(IV) compounds: recent advances

Organotin(IV) compounds have been considered for their outstanding industrial, medical and specific applications in the synthesis of various types of chemical compounds. In this review, we have focused on the structural chemistry of organotin(IV) compounds, including coordination chemistry, the effect of structure on reactions, bond formations from the perspective of structure and investigation of the structure of organotin(IV) compounds in different phases. The structural chemistry of organotin(IV) compounds is subject to interest due to their major impact on predicting the properties and drumming up support for pushing back the frontiers of synthesis of organotin(IV) compounds with advanced properties.

Isonitriles as Stereoelectronic Chameleons: The Donor-Acceptor Dichotomy in Radical Additions

Radical addition to isonitriles (isocyanides) starts and continues all the way to the transition state (TS) mostly as a simple addition to a polarized π-bond. Only after the TS has been passed, the spin density moves to the α-carbon to form the imidoyl radical, the hallmark intermediate of the 1,1-addition-mediated cascades. Addition of alkyl, aryl, heteroatom-substituted, and heteroatom-centered radicals reveals a number of electronic, supramolecular, and conformational effects potentially useful for the practical control of isonitrile-mediated radical cascade transformations. Addition of alkyl radicals reveals two stereoelectronic preferences. First, the radical attack aligns the incipient C···C bond with the aromatic π-system. Second, one of the C-H/C-C bonds at the radical carbon eclipses the isonitrile N-C bond. Combination of these stereoelectronic preferences with entropic penalty explains why the least exergonic reaction (addition of the t-Bu radical) is also the fastest. Heteroatomic radicals reveal further unusual trends. In particular, the Sn radical addition to the PhNC is much faster than addition of the other group IV radicals, despite forming the weakest bond. This combination of kinetic and thermodynamic properties is ideal for applications in control of radical reactivity via dynamic covalent chemistry and may be responsible for the historically broad utility of Sn radicals ("the tyranny of tin"). In addition to polarity and low steric hindrance, radical attack at the relatively strong π-bond of isonitriles is assisted by "chameleonic" supramolecular interactions of the radical center with both the isonitrile π*-system and lone pair. These interactions are yet another manifestation of supramolecular control of radical chemistry.