Dual Photoredox/Copper Catalyzed Fluoroalkylative Alkene Difunctionalization

Abstract

A method for performing radical difunctionalization of alkenes using fluorinated halides and a nucleophilic component (thiolate and iodide anions) is described. These nucleophilic fragments serve as redox active groups for performing subsequent transformations. The difunctionalization reaction involves photoredox generation of fluorinated radicals, their addition to the double bond followed by copperpromoted C−S or C−I bond formation. The primary products can be further coupled with silyl enol ethers, α-(trifluoromethyl)styrenes, and trimethylsilyl cyanide affording a variety of fluorinated compounds.

Photo‐induced Desulfurative Processes for Carbon Radical Generation

“…[28][29][30][31] On the other hand, the desulfurization of the second class of thioethers (D or G) can be achieved by initial SET reduction of thioethers containing either tetra-fluoropyridine or thiazolium cores (Scheme 8B). [32][33][34][35][36][37][38][39][40] The splitting of the CÀ S bond in the radicals E or H then leads to the carbon radicals and either a stabilized thiolate F or the 3methylthiazolidine-2-thione J byproduct.…”

“…[32] Their strategy employed 2-mercaptothiazolines 31 which are readily obtained from aliphatic thiol, halide or alcohol precursors or from the functionalization of double bonds. [32,33] The in situ transformation to the corresponding 2-mercaptothiazolium salts 32 using methyl triflate provided easy to reduce substrates as shown by cyclic voltammetry. In the presence of the [Ir(dtbbpy)(ppy) 2 ]PF 6 photocatalyst under blue light irradiation, CÀ S bond cleavage occurred in 32 providing secondary alkyl radicals as well as stabilized and non-stabilized primary alkyl radicals which reacted with silylated enol ethers 33 at room temperature to form the corresponding alkylated ketones 34 (Scheme 12).…”

“…Cyanation and reduction of fluorinated PyfS derivatives. [33,37] was described (Scheme 18). [39] A large variety of PyfS precursors 63, including primary, secondary and tertiary alkyls, were reacted with bis(catechol)borane B 2 cat 2 64 in DMF under 400 nm LED irradiation in the presence of 3DPA2FBN photocatalyst.…”

“…In addition to the above-mentioned synthetic pathways for fluorinated PyfS derivatives, these interesting precursors can also be synthesized by the difunctionalization of alkenes. [33,37] Miscellaneous light-mediated transformations of these PyfS precursors 51 include the cyanation using TMSCN 52 to afford 53 and the reduction using Hantzsch ester 54 to provide 55 (Scheme 16).…”