Electrochemical oxidative cascade cyclization of olefinic amides and alcohols leading to the synthesis of alkoxylated 4H-3,1-benzoxazines and indolines

Abstract

Synthesis technology can be used directly and selectively to construct two different heterocycles from one substrate. Herein, we introduce a mild and efficient electrochemical oxidative strategy to construct alkoxylated 4H-3,1-benzoxazines...

Electrochemical Thiocyanation/Cyclization Cascade to Access Thiocyanato-Containing Benzoxazines

“…1 H NMR (400 MHz, CDCl 3 ) δ 8.33-8.23 (m, 2H), 7.77-7.69 (m, 2H), 7.45-7.34 (m, 2H), 7.34-7.25 (m, 1H), 7.14 (dd, J = 7.6, 1.4 Hz, 1H), 3.58 (d, J = 14.1 Hz, 1H), 3.46 (d, J = 14.1 Hz, 1H), 1.91 (s, 3H). 13 [1,3]oxazine (3i). Colorless oil was obtained in 77% isolated yield, 70.5 mg, 0.3 mmol scale, Rf = 0.35 (petroleum ether/ethyl acetate = 10:1).…”

“…To date, the flourishing development of radical chemistry has provided attractive protocols to access heterocycles via cascade routes [7][8][9][10][11][12][13]. Utilizing radicals as functional reagents, the complicated heterocycles could be effectively obtained under mild conditions.…”

“…H NMR (400 MHz, CDCl 3 ) δ 8.11-7.96 (m, 2H), 7.40-7.30 (m, 2H), 7.28-7.19 (m, 3H), 7.11 (dd, J = 7.4, 1.2 Hz, 1H), 3.54 (d, J = 13.8 Hz, 1H), 3.41 (d, J = 13.8 Hz, 1H), 2.40 (s, 3H), 1.88 (s, 3H) 13. C NMR (101 MHz, CDCl 3 ) δ 155.4, 142.3, 138.7, 129.8, 129.0, 128.9, 127.9, 126.9, 126.2, 125.7, 122.8, 112.2, 78.6, 44.2, 25.6, 21.5.…”

Research progress in electrochemical/photochemical utilization of methanol as a C1 source

“…Mo and co-workers 21 developed a novel electrochemical cyclization strategy. This method uses olefinic amides ( 37 ) as substrates and methanol as the C1 source.…”

Metal-free electrochemical oxidative intramolecular cyclization ofN-propargylbenzamides: facile access to oxazole ketals

“…Inspired by the systematic studies of Xu's team in the field of electrochemically driven cyclization reactions initiated by a nitrogen-centered radical, 11 we speculated that the anodic oxidation of N -propargylamides could generate a nitrogen-centered radical, which then rearranged into an oxygen-centered radical, followed by 5- exo-dig radical cyclization and a consecutive anodic oxidation and nucleophilic substitution process, achieving the synthesis of oxazole ketals. Herein, we report an electrochemically driven 5- exo-dig radical cyclization reaction of N -propargylbenzamides with alcohols, 12 enabling the synthesis of oxazole ketals in an undivided cell under mild conditions, which avoids the use of any stoichiometric oxidants, metal catalysts, acids, and complex reaction systems (Scheme 1d).…”