A General Strategy for Aliphatic C–H Functionalization Enabled by Organic Photoredox Catalysis
摘要:
Synthetic transformations that functionalize unactivated aliphatic C-H bonds in an intermolecular fashion offer unique strategies for the synthesis and late stage derivatization of complex molecules. Herein we report a general approach to the intermolecular functionalization of aliphatic C-H bonds using an acridinium photoredox catalyst and phosphate salt under blue LED irradiation. This strategy encompasses a range of valuable C-H transformations, including the direct conversions of a C-H bond to C-N, C-F, C-Br, C-Cl, C-S, and C-C bonds, in all cases using the alkane substrate as the limiting reagent. Detailed mechanistic studies are consistent with the intermediacy of a putative oxygen-centered radical as the hydrogen atom-abstracting species in these processes.
A general and convenient copper-mediated trifluoromethylthiolation of primary and secondary alkyl halides was described. Variation of the solvent, additives and time allowed optimization of the reaction. A wide range of alkyl halides were explored to give a set of alkyl trifluoromethyl thioethers in moderate to excellent yields. A variety of functional groups, including ethers, thioether, esters, nitriles, amides, and ketal groups, were well tolerated in the electrophilic partner.
A practical and efficient method for the direct trifluoromethylthiolation of unactivated C(sp3)H bonds by AgSCF3/K2S2O8 under mild conditions is described. The reaction has a good functional‐group tolerance and good selectivity. Initial mechanistic investigations indicate that the reaction may involve a radical process in which K2S2O8 plays key roles in both the activation of the C(sp3)H bond and
Photocatalytic C–H Trifluoromethylthiolation by the Decatungstate Anion
作者:Tobias E. Schirmer、Alessa B. Rolka、Tobias A. Karl、Ferdinand Holzhausen、Burkhard König
DOI:10.1021/acs.orglett.1c01870
日期:2021.8.6
A broadly applicable method for the trifluoromethylthiolation of methylene C(sp3)–H, methine C(sp3)–H, α-oxygen C(sp3)–H, and formyl C(sp2)–H bonds is presented using the decatungstate anion as the sole catalyst. By adjusting the substrate ratio and reaction concentration, this method was applied to 40 examples in good regioselectivities, including the derivatization of natural products. Furthermore