Multicomponent Oxidative Trifluoromethylation of Alkynes with Photoredox Catalysis: Synthesis of α-Trifluoromethyl Ketones

Abstract

The direct oxidative addition of CF and HO to alkynes was achieved with photoredox catalysis to obtain α-trifluoromethyl ketones via rapid enol-keto tautomerization. The reaction exhibits high functional group tolerance and regioselectivity. Heterocycles of various sizes containing CF were synthesized from the α-CF-substituted diketones obtained through the protocol, thereby demonstrating the versatile applicability of the method. Mechanistic studies of the reaction with isotopes provided insight into the reaction pathway.

Visible light promoted difunctionalization reactions of alkynes

“…According to Koike and Akita in 2015 [79], using Ir(ppy)2(dtbbpy)(PF6) as a photocatalyst and 2,6-ditertbutylpyridine as a base, internal aryl alkynes and Umemoto reagent were converted into tetra-substituted trifluoromethylated alkenes in 30%-86% yields, and 61/39 to 97/3 E/Z ratios. Similar strategies were conducted by Wu [80] and Han [81,82] to achieve intramolecular trifluoromethylation cyclization and oxidative trifluoromethylation reactions, respectively (Scheme 7).…”

A Convenient Procedure for Sonogashira Reactions Using Propyne

“…As seen in Scheme 2, both electron-rich and electrondeficient aromatic iodides provide products 1-7. [9][10][11][12][13][14] Synthesis of the phenolic ester 7 14 provided an excellent precursor of some natural products. Employing our previously reported work on ozonolysis, 15 we ozonized alkyne 7.…”

Recent Advances in Photoredox Methods for Ketone Synthesis

“…The α‐trifluoromethyl ketones were accessed via photoredox multicomponent oxidative trifluoromethylation of alkynes by Han et al ., using 5‐(trifluoromethyl)dibenzothiophenium trifluoromethanesulfonate (Umemoto's reagent) (Scheme ) . The reaction involves generation of CF 3 radical 63 a from Umemoto's reagent on SET with photocatalyst.…”