The synthesis of sulfonated 4H-3,1-benzoxazines via an electro-chemical radical cascade cyclization

Abstract

We achieved sulfonated 4H-3,1-benzoxazines under ambient conditions without any metals and external chemical oxidants via electrochemical radical cascade cyclizations.

The preparation and applications of amides using electrosynthesis

“…80 recently been produced by electrochemical radical cascade cyclisation as reported by He and co-workers. 86 Such a wealth of highly sustainable and green electrosynthetic methods for producing heterocycles from amides provides a very promising foundation for future preparations of valuable pharmaceuticals and agrochemicals, which are largely comprised of heterocyclic compounds.…”

Oxidative Sulfonylation of Multiple Carbon‐Carbon bonds with Sulfonyl Hydrazides, Sulfinic Acids and their Salts

“…[275] Electric current was also used as the oxidant for this transformation. [276] Radical traps experiments showed that the reaction proceeded through the generation of sulfonyl radical A from sulfinate anion 523 under oxidative conditions, which was then added to the double bond of o-vinylanilide 522 with the formation of C-centered radical B. The final benzoxazines 524 are formed as a result of subsequent oxidation of radical B into cation C, intramolecular nucleophilic attack, and deprotonation (Scheme 226).…”

“…AgNO 3 ‐ or CAN‐mediated reaction of o ‐vinylanilides 522 with sodium sulfinates 523 under an inert atmosphere led to benzoxazines 524 (Scheme 225). [275] Electric current was also used as the oxidant for this transformation [276] . Radical traps experiments showed that the reaction proceeded through the generation of sulfonyl radical A from sulfinate anion 523 under oxidative conditions, which was then added to the double bond of o ‐vinylanilide 522 with the formation of C‐centered radical B .…”

Recent Progress in Sulfonylation via Radical Reaction with Sodium Sulfinates, Sulfinic Acids, Sulfonyl Chlorides or Sulfonyl Hydrazides

“…In 2019, the electrochemical radical cascade cyclizations of styrenyl amides with sulfonylhydrazines for the synthesis of sulfonated 4H-3,1-benzoxazines was developed by Huang group. [120] No metal or oxidant was need for this reaction. CV (Cyclic voltammograms) experiments showed that sulfonylhydrazines was oxidized preferentially over styrenyl amides in this electrolysis process.…”

“…In 2019, the electrochemical radical cascade cyclizations of styrenyl amides with sulfonylhydrazines for the synthesis of sulfonated 4H‐3,1‐benzoxazines was developed by Huang group [120] . No metal or oxidant was need for this reaction.…”