CF₃SO₂Na-Mediated Visible-Light-Induced Cross-Dehydrogenative Coupling of Heteroarenes with Aliphatic C(sp³)–H Bonds

Abstract

Minisci-type reaction is one of the important means to construct C­(sp3)–H functionalization of heteroarenes. According to traditional methods, stoichiometric amounts of precious transition metal catalysts and chemical oxidants were required at high temperatures. Here, a green and gentle novel Minisci-type method was developed via visible-light-induced cross-dehydrogenative coupling of heteroarenes with aliphatic C­(sp3)–H bonds under oxidant-free and transition-metal-catalyst-free conditions. Only the catalytic equivalent of CF3SO2Na and room temperature were required to maintain an efficient reaction.

One‐Carbon Ring Expansion of Indoles and Pyrroles: A Straightforward Access to 3‐Fluorinated Quinolines and Pyridines

“…Site-selective radical crossdehydrogenative coupling of 3-fluoro-2-phenylquinoline ( 8) with 1,4-dioxane proceeded smoothly to produce polysubstituted quinoline 49. [18] Hydrogenation of 3-fluoro-2-phenylquinoline (8) with Hantzsch ester provided a direct route to fluorinated tetrahydroquinoline 50, [19] in contrast to previous multi-step synthesis. [20] In addition, quinoline-1-oxide 51 was efficiently accessed via the oxidation of quinoline 8 with m-CPBA.…”

“…To document the synthetic value of the 3‐fluorinated quinoline products, subsequent structural modifications were performed (Figure 3C). Site‐selective radical cross‐dehydrogenative coupling of 3‐fluoro‐2‐phenylquinoline ( 8 ) with 1,4‐dioxane proceeded smoothly to produce polysubstituted quinoline 49 [18] . Hydrogenation of 3‐fluoro‐2‐phenylquinoline ( 8 ) with Hantzsch ester provided a direct route to fluorinated tetrahydroquinoline 50 , [19] in contrast to previous multi‐step synthesis [20] .…”

“…Electron-deficient indoles (5, 10) proceeded smoothly, although increased loading of LiO t Bu and dibromofluoromethane (2) were crucial for a high conversion of the indoles. Especially, 4-and/or 7-substituted indoles (18,23,24), that are [a] entry variation from standard conditions yield of 3 (%) [b] 1…”

Aliphatic C–H arylation with heteroarenes without photocatalysts

“…), elevated temperatures and substrates with coordinating directing groups. [17][18][19][20][21] Recently, visible-light-induced photoredox catalysis has emerged as a powerful platform for aliphatic C-H arylation. [22][23][24][25][26] Successful realization of such transformations lies in the hydrogen atom transfer (HAT) between alkanes and Scheme 1 Aliphatic C-H arylation with heteroarenes.…”

Photoinduced Pd-Catalyzed Csp2–H/Csp3–H Dehydrocoupling Reaction Employing Polyhaloaromatics as the Dehydrogenating Agent

“…Direct C–H dehydrocoupling is an important strategy for C–C bond construction since it avoids prefunctionalization of C–H bonds and thereby achieves step economy in synthetic chemistry . Thereinto, establishing C sp2 –C sp3 by this strategy is expansively applied in pharmaceuticals .…”