Anti-Markovnikov hydro(amino)alkylation of vinylarenes via photoredox catalysis

Abstract

Photoredox catalysis is a powerful means to generate odd-electron species under mild reaction conditions from a wide array of radical precursors. Herein, we present the application of this powerful catalytic manifold to address the hydroalkylation and hydroaminoalkylation of electronically diverse vinylarenes. This reaction allows for generalized alkene hydroalkylation leveraging common alkyl radical precursors, such as organotrifluoroborate salts and carboxylic acids. Furthermore, utilizing easily accessible α-silyl amine reagents or tertiary amines directly, secondary and tertiary amine moieties can be installed onto monoaryl and diaryl alkenes to access valuable products, including γ,γ-diarylamines pharmacophores. Thus, under a unified system, both hydroalkylation and hydroaminoalkylation of alkenes are achieved. The substrate scope is evaluated through 57 examples, the synthetic utility of the method is demonstrated, and preliminary mechanistic insights are presented.

Photoredox-Catalyzed Oxidation of Anions for the Atom-Economical Hydro-, Amido-, and Dialkylation of Alkenes

“…Stable organic anions such as carboxylates, − borates, − silicates, − and sulfinates have been shown to undergo photoredox-catalyzed oxidation, followed by fragmentation to generate carbon-centered radical intermediates that participate in a wide variety of interesting transformations. ,, We envisioned that anion oxidation could be expanded to low-p K a organic molecules that form stable anions such as 1,3-dicarbonyls and amides. The inherently electron-rich nature of these anions, coupled with the SET capabilities of photoredox catalysts, should facilitate productive oxidation events if the resulting radical species are thermodynamically stable enough to favor a forward reaction.…”

Photoinduced Three-Component Carboarylation of Unactivated Alkenes with Protic C(sp3)–H Feedstocks

“…Notwithstanding their importance, synthesizing these structural moieties has attracted extensive attention from scientists. The conventional approaches mainly relied on the electrophilic substitution of the 2-benzylicpyridine with strong bases or involved the addition of 2-(1-phenylvinyl)­pyridine . However, the starting materials such as 2-benzylicpyridine and 2-(1-phenylvinyl)­pyridine were required to be prepared, which resulted in diminished atom and step economy of these transformations.…”

In-Catalyzed Transfer Hydrogenation and Regioselective Hydrogen–Deuterium Addition to the Olefins

“…1 H NMR (400 MHz, CDCl 3 ) δ 7.30−7.27 (m, 2H), 7.23−7.16 (m, 3H), 7.13− 7.08 (m, 4H), 4.12 (q, J = 7.2 Hz, 1H), 2.31 (s, 3H), 1.63 (d, J = 7.1 Hz, 3H). 13 C{ 1 H} NMR (101 MHz, CDCl 3 ) δ 146. 7, 143.5, 135.6, 129.2, 128.5, 127.7, 127.6, 126.1, 44.5, 22.1, 21. 131.5, 129.5, 128.6, 127.7, 126.4, 119.9, 44.3, 21.9.…”