Photoredox Catalysis Induced Bisindolylation of Ethers/Alcohols via Sequential C-H and C-O Bond Cleavage.

A visible-light-engaged 2-fold site-selective alkylation of indole derivatives with aliphatic ethers or alcohols has been accomplished for easy access to symmetric 3,3'-bisindolylmethane derivatives. The experimental data suggest a sequential photoredox catalysis induced radical addition and proton-mediated Friedel-Crafts alkylation mechanism.

Manganese-catalyzed synthesis of monofluoroalkenes via C-H activation and C-F cleavage.

The manganese-catalyzed α-fluoroalkenylation of arenes via C-H activation and C-F cleavage has been described. This protocol provides a very useful method for the synthesis of monofluoroalkenes with predominant unconventional E-isomer selectivity which complements the existing strategies for the access to these molecular architectures. In addition, the selectivity of ß-defluorination in the catalytic cycle not only determines the configurations of the products but also obviates the use of external oxidants, providing a good example in the exploitation of manganese-catalyzed redox-neutral C-H transformations.

Switchable C-H Functionalization of N-Tosyl Acrylamides with Acryloylsilanes.

A controllable Rh-catalyzed protocol to access alkylation and alkenylation-annulation of N-tosyl acrylamide with acryloyl silane is reported. In contrast to the directing group or catalyst-dependent divergent sp2 C-H alkylation/alkenylation, the intrinsic property of acryloylsilane allows the switchable reaction manifold, thereby affording either alkylation or annulation products with slight modification of the reaction conditions.

F- Nucleophilic-Addition-Induced Allylic Alkylation.

Herein we present a novel strategy based on palladium-catalyzed allylic alkylation by taking advantage of the nucleophilic addition of external fluoride onto gem-difluoroalkenes as the initiation step. The merit of this protocol is highly appealing, as it enables a formal allylation of trifluoroethylarene derivatives through the in situ generation of ß-trifluorocarbanions, which otherwise are deemed to be problematic in deprotonative allylation. Furthermore, this strategy distinguishes itself by high modularity, operational simplicity, and wide substrate scope with respect to allyl carbonates, giving rise to a broad array of homoallyltrifluoromethane derivatives, which otherwise would not be easily obtained using existing synthetic methods.

Anomalous Reactivity and Selectivity in the Intermolecular Diels-Alder Reactions of Multisubstituted Acyclic Dienes with Geometrical Isomers of Enals.

A Lewis-acid catalyzed intermolecular Diels-Alder reaction between multisubstituted acyclic dienes and the E and Z isomers of α,ß-enals was studied. It was found that the diene reacted selectively with the Z-isomer of the α,ß-enal.

Palladium-catalyzed difunctionalization of internal alkynes via highly regioselective 6-endo cyclization and alkenylation of enynoates: synthesis of multisubstituted pyrones.

An efficient Pd(II)-catalyzed difunctionalization reaction of internal alkynes is reported. In this reaction, various enynoates and electron-deficient alkenes were used for the syntheses of useful highly substituted pyrone derivatives via a 6-endo cyclization and subsequent alkenylation pathway. The corresponding products could be obtained in moderate to good yields under very mild reaction conditions. The high regioselectivity and wide compatibility with different functional groups found in the desired products demonstrate this method to be a general and useful tool for the synthesis of highly substituted pyrone derivatives.