Continuous-flow electro-oxidative coupling of sulfides with activated methylene compounds leading to sulfur ylides

Liu, Chengkou; Lin, Yang; Cai, Chen; Yuan, Chengcheng; Fang, Zheng; Guo, Kai

doi:10.1039/d1gc00226k

Cited by 22 publications

(18 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, a slight lower oxidation peak of 3 (1.47 V, black, Figure b) than that of BHT was observed. The results above revealed that the inclusion of a radical scavenger did not inhibit the oxidation of catalysts and reactants and provided strong support for the existence of radical process . No obvious inhibition on reaction efficiency was observed in the presence of DABCO or in the dark, which ruled out the involvement of photosensitized singlet oxygenation (Scheme c).…”

Section: Resultsmentioning

confidence: 73%

“…The results above revealed that the inclusion of a radical scavenger did not inhibit the oxidation of catalysts and reactants and provided strong support for the existence of radical process. 82 No obvious inhibition on reaction efficiency was observed in the presence of DABCO or in the dark, which ruled out the involvement of photosensitized singlet oxygenation 83 (Scheme 3c). Good yield was obtained when the reaction was conducted in the presence of superoxide radical anion (O 2…”

Section: ■ Results and Discussionmentioning

confidence: 97%

See 1 more Smart Citation

Organocatalytic Electrosynthesis of Cinnolines through Cascade Radical Cyclization and Migration

Cai

Yuan

et al. 2021

ACS Sustainable Chem. Eng.

Self Cite

View full text Add to dashboard Cite

A straightforward one-pot two-step electrosynthesis of cinnoline derivatives from ortho-alkynyl acetophenones and sulfonyl hydrazides has been developed through the organocatalytic cascade radical cyclization and migration. This methodology features green and mild reaction conditions, good to excellent yield, broad functional group tolerance, excellent regioselectivity, and use of readily available substrates. Moreover, based on isotope labeling, radical trapping, singlet oxygen and superoxide radical anion inhibiting, cyclic voltammetry, and EPR experiments, a possible electrochemically cascade radical cyclization and migration process was proposed.

show abstract

Section: Resultsmentioning

confidence: 73%

Section: ■ Results and Discussionmentioning

confidence: 97%

Organocatalytic Electrosynthesis of Cinnolines through Cascade Radical Cyclization and Migration

Cai

Yuan

et al. 2021

ACS Sustainable Chem. Eng.

Self Cite

View full text Add to dashboard Cite

show abstract

“…We also succeeded in converting a sterically congested tetrasubstituted alkene to cyclopropyl ketone 51 . Note that this electrocatalytic system is not applicable to intermolecular cyclopropanation, likely because of competitive direct coupling of the phenothiazine catalyst with the active methylene compounds to form sulfur ylides …”

Section: Resultsmentioning

confidence: 99%

Organoelectrocatalysis Enables Direct Cyclopropanation of Methylene Compounds

et al. 2022

View full text Add to dashboard Cite

Cyclopropane is a prevalent structural unit in natural products and bioactive compounds. While the transition metal-catalyzed alkene cyclopropanation of functionalized compounds such as α-diazocarbonyl derivatives has been well established and provides straightforward access to cyclopropanes, cyclopropanation directly from the more stable and simpler methylene compounds has remained an unsolved challenge despite the highly desirable benefits of minimal prefunctionalization and increased operational safety. Herein we report an electrocatalytic strategy for the cyclopropanation of active methylene compounds, employing an organic catalyst. The method shows a broad substrate scope and excellent scalability, requires no metal catalyst or external chemical oxidant, and provides convenient access to several types of cyclopropane-fused heterocyclic and carbocyclic compounds. Mechanistic investigations suggest that the reactions proceed through a radical–polar crossover process to form the two new carbon–carbon bonds in the nascent cyclopropane ring.

show abstract

“…Ylides derived from functionalization of the sulfur of aryl phenothiazines have previously been reported. 25 Further attempted transformations by quenching with an electrophile other than a proton revealed this could not readily be turned into a three-component coupling. Attempting to quench the presumed organomagnesium intermediate formed after addition of the phenothiazide to the benzyne with either diphenylchlorophosphine 5a or Weinreb amide 5b did not result in productive formation of compounds 6a or 6b (Equation 2, Scheme 3).…”

Section: Scheme 3 Limitations In Scopementioning

confidence: 99%

Gram-Scale Synthesis of the N-Phenyl Phenothiazine Photocatalyst by Benzyne Addition

Welsh

Robertson²,

Speed

2021

Preprint

View full text Add to dashboard Cite

N-phenyl phenothiazine is one of the most reducing photoredox catalysts. Its synthesis commonly requires transition metal catalyzed cross-coupling reactions. Here we show the syntheses of four aryl phenothiazines via a benzyne route, including a multi-gram scale synthesis of N-phenyl phenothiazine. While yields are modest, the simplicity, low cost, and lack of requirement for cross-coupling catalyst in this synthesis will be attractive to users of this photocatalyst.

show abstract

Continuous-flow electro-oxidative coupling of sulfides with activated methylene compounds leading to sulfur ylides

Abstract: An unprecedentedly straightforward electro-oxidative coupling of sulfide with activated methylene compound to synthesize sulfur ylide has been developed. Good to excellent yields can be obtained under catalyst- and oxidant-free conditions...

Cited by 22 publications

References 72 publications

Organocatalytic Electrosynthesis of Cinnolines through Cascade Radical Cyclization and Migration

Organocatalytic Electrosynthesis of Cinnolines through Cascade Radical Cyclization and Migration

Organoelectrocatalysis Enables Direct Cyclopropanation of Methylene Compounds

Gram-Scale Synthesis of the N-Phenyl Phenothiazine Photocatalyst by Benzyne Addition

Contact Info

Product

Resources

About