Mn‐Catalyzed Electrochemical Synthesis of Quinazolinones from Primary Alcohols/Benzyl Ethers and o‐Aminobenzamides

Abstract

An efficient approach for the synthesis of quinazolinones from o‐aminobenzamides and alcohols by the combination of electrochemistry and redox‐metal catalysis has been developed. Taking manganese(II) sulfate as a redox catalyst, this transformation proceeded smoothly under ambient conditions in an undivided cell to afford quinazolinones in moderate to excellent yields with a wide substrate scope. Benzyl ethers were also suitable participants in the cascade cyclization sequence.

Metal‐ and Catalyst‐Free Electrochemical Synthesis of Quinazolinones from Alkenes and 2‐Aminobenzamides

“…The cyclic voltammetry (CV) of each reaction was recorded as shown in Figure . An oxidation peak was observed for the reaction of 1 a at Ep=1.59 V vs SCE, in the region of 0.0–3.0 V vs Ag/AgCl, which was markedly weakened (Figure , curve b). However, the cyclic voltammogram of the reaction of 2 a showed an oxidation peak at Ep=2.15 V (Figure , curve c).…”

“…The condensation of 4 c with 1 a affords imine B and releases H 2 O, and the subsequent intramolecular cyclization forms C . Finally, the rapid anodic oxy‐dehydrogenation of C yields the desired product, quinazolinone 3 c . On the cathode, protons are reduced to hydrogen to complete the electrochemical cycle.…”

Electrifying green synthesis: recent advances in electrochemical annulation reactions

“…Recently, Huang and co-workers developed an efficient approach for the synthesis of quinazolinones 34 from o-aminobenzamides 33 and alcohols 32 by the combination of electrochemistry and a redox-metal catalyst (Scheme 9). 49 The authors describe the first Mn catalysed cascade cyclization reaction to afford quinazolinones. Primary benzylic alcohols bearing electron-donating or electron-withdrawing groups were evaluated, and also, sterically hindered substrates.…”

Catalytic Electrosynthesis of N,O‐Heterocycles – Recent Advances

“…In 2019 Lin and co‐workers developed a simple and efficient approach toward quinazolinones 12 , starting from available 2‐aminobenzamides 9 and alcohols 10 or benzyl methyl ethers 11 (Scheme ). Using MnSO 4 as a redox mediator the authors realized a cascade cyclization sequence in ambient conditions to produce quinazolinones 12 in good to excellent yields.…”