A manganese-catalyzed highly site-and enantioselective benzylic C−H azidation of indolines has been described. The practical method is applicable for azidation of a tertiary benzylic C−H bond with good functional group tolerance, allowing facile access to structurally diverse tertiary azide-containing indolines in high efficiency with excellent site-, chemo-, and enantioselectivity. The generality of the method was further demonstrated by site-and enantioselective azidation of the secondary benzylic C−H bond for a range of secondary azide-containing indolines. The benzylic C−H azidation method allows to straightforwardly and enantioselectively install a variety of nitrogen-based functional groups and diverse bioactive molecules at the C 3 position of indoline frameworks through post-azidation manipulations. Gram-scale synthesis was also demonstrated, further highlighting the synthetic potential of the method. Mechanistic studies by combined experiments and computations elucidated the reaction mechanism and origins of stereoselectivity.
A manganese-catalyzed oxidative kinetic resolution of cyclic benzylic ethers through asymmetric C(sp 3) À H oxidation is reported. The practical approach is applicable to a wide range of 1,3-dihydroisobenzofurans bearing diverse functional groups and substituent patterns at the a position with extremely efficient enantiodiscrimination. The generality of the strategy was further demonstrated by efficient oxidative kinetic resolution of another type of five-membered cyclic benzylic ether, 2,3-dihydrobenzofurans, and six-membered 6H-benzo[c]chromenes. Direct late-stage oxidative kinetic resolution of bioactive molecules that are otherwise difficult to access was further explored.
Diarylmethyl alkynes with chirality at the propargylic position are privileged building blocks in many biologically important molecules. However, catalytic asymmetric access to such moieties has remained underdeveloped. Herein, we described...
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