Insertion Reaction of 2-Halo-N-allylanilines with K2S Involving Trisulfur Radical Anion: Synthesis of Benzothiazole Derivatives under Transition-Metal-Free Conditions

Synthesis ◽  
2020 ◽  
Author(s):  
Yan-Wei Zhao ◽  
Shun-Yi Wang ◽  
Xin-Yu Liu ◽  
Tian Jiang ◽  
Weidong Rao
Keyword(s):  
Transition Metal ◽  
Radical Anion ◽  
Radical Cyclization ◽  
Transition Metal Catalysis ◽  
Insertion Reaction ◽  
Metal Catalysis ◽  
Metal Free ◽  
Benzothiazole Derivatives

AbstractA synthesis of benzothiazole derivatives through the reaction of 2-halo-N-allylanilines with K2S in DMF is developed. The trisulfur radical anion S3·–, which is generated in situ from K2S in DMF, initiates the reaction without transition-metal catalysis or other additives. In addition, two C–S bonds are formed and heteroaromatization of benzothiazole is triggered by radical cyclization and H-shift.

Retaining Alkyl Nucleophile Regiofidelity in Transition-Metal-Mediated Cross-Couplings to Aryl Electrophiles

Synthesis ◽  
2018 ◽  
Vol 50 (20) ◽  
pp. 3974-3996 ◽  
Author(s):  
Josep Cornella ◽  
Matthew O’Neill
Keyword(s):  
Transition Metal ◽  
Functional Group ◽  
Chemical Space ◽  
Cross Coupling ◽  
Transition Metal Catalysis ◽  
Metal Catalysis ◽  
Substantial Progress ◽  
Tertiary Alkyl ◽  
Metal Ligand

While the advent of transition-metal catalysis has undoubtedly transformed synthetic chemistry, problems persist with the introduction of secondary and tertiary alkyl nucleophiles into C(sp2) aryl electrophiles. Complications arise from the delicate organometallic intermediates typically invoked by such processes, from which competition between the desired reductive elimination event and the deleterious β-H elimination pathways can lead to undesired isomerization of the incoming nucleophile. Several methods have integrated distinct combinations of metal, ligand, nucleophile, and electrophile to provide solutions to this problem. Despite substantial progress, refinements to current protocols will facilitate the realization of complement reactivity and improved functional group tolerance. These issues have become more pronounced in the context of green chemistry and sustainable catalysis, as well as by the current necessity to develop robust, reliable cross-couplings beyond less explored C(sp2)–C(sp2) constructs. Indeed, the methods discussed herein and the elaborations thereof enable an ‘unlocking’ of accessible topologically enriched chemical space, which is envisioned to influence various domains of application.1 Introduction2 Mechanistic Considerations3 Magnesium Nucleophiles4 Zinc Nucleophiles5 Boron Nucleophiles6 Other Nucleophiles7 Tertiary Nucleophiles8 Reductive Cross-Coupling with in situ Organometallic Formation9 Conclusion

Metal-Free Catalytic Aromatic C–H Borylation

Synlett ◽  
2020 ◽  
Vol 31 (19) ◽  
pp. 1857-1861
Author(s):  
Hua Zhang ◽  
Li Wang
Keyword(s):  
Transition Metal ◽  
Recent Progress ◽  
Rapid Development ◽  
Transition Metal Catalysis ◽  
Mechanistic Studies ◽  
Metal Catalysis ◽  
Promising Alternative ◽  
Metal Free ◽  
History Of ◽  
Near Future

In recent decades, C–H borylation has undergone rapid development and has become one of the most important and efficient methods for the synthesis of organoboron compounds. Although transition-metal catalysis dominates C–H borylation, the metal-free approach has emerged as a promising alternative strategy. This article briefly summarizes the history of metal-free aromatic C–H borylation, including early reports on electrophilic C–H borylation and recent progress in metal-free catalytic intermolecular C–H borylation; it also highlights our recent work on BF3·Et2O-catalyzed C2–H borylation of hetarenes. Despite these recent advances, comprehensive mechanistic studies on various metal-free catalytic aromatic C–H borylations and novel processes with a wider substrate scope are eagerly expected in the near future.

scholarly journals The involvement of the trisulfur radical anion in electron-catalyzed sulfur insertion reactions: facile synthesis of benzothiazine derivatives under transition metal-free conditions

2016 ◽  
Vol 7 (7) ◽  
pp. 4067-4072 ◽  
Author(s):  
Zheng-Yang Gu ◽  
Jia-Jia Cao ◽  
Shun-Yi Wang ◽  
Shun-Jun Ji
Keyword(s):  
Transition Metal ◽  
Radical Anion ◽  
Insertion Reaction ◽  
Insertion Reactions ◽  
Facile Synthesis ◽  
Metal Free ◽  
Practical Synthesis

An efficient and practical synthesis of benzothiazine by K2S initiated sulfur insertion reaction with enaminones via electron catalysis is developed.

Transition-metal-catalyzed nucleophilic dearomatization of electron-deficient heteroarenes

Synthesis ◽  
2021 ◽  
Author(s):  
Jie Jia ◽  
Fangdong Hu ◽  
Ying Xia
Keyword(s):  
Transition Metal ◽  
Asymmetric Catalysis ◽  
Short Review ◽  
Transition Metal Catalysis ◽  
Powerful Method ◽  
Metal Catalysis ◽  
Unique Method ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

Transition-metal-catalyzed nucleophilic dearomatization of electron-deficient heteroarenes, such as pyridines, quinolines, isoquinolines and nitroindoles, has become a powerful method for the access of unsaturated heterocycles in recent decades. This short review summarizes nucleophilic dearomatization of electron-deficient heteroarenes with carbon- and heteroatom-based nucleophiles via transition-metal catalysis. A great number of functionalized heterocycles were obtained in this transformation. Importantly, many of these reactions were carried out in an enantioselective manner by means of asymmetric catalysis, providing a unique method for the construction of enantioenriched heterocycles. 1 Introduction 2 Transition-metal-catalyzed nucleophilic dearomatization of heteroarenes via alkynylation 3 Transition-metal-catalyzed nucleophilic dearomatization of heteroarenes via arylation 4 Transition-metal-catalyzed nucleophilic dearomatization of heteroarenes with other nucleophiles 5 Transition-metal-catalyzed nucleophilic dearomatization with nucleophiles formed in situ 6 Conclusion and outlook

scholarly journals Last Decade of Unconventional Methodologies for the Synthesis of Substituted Benzofurans

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2327 ◽  
Author(s):  
Lucia Chiummiento ◽  
Rosarita D’Orsi ◽  
Maria Funicello ◽  
Paolo Lupattelli
Keyword(s):  
Natural Products ◽  
Transition Metal ◽  
Intramolecular Cyclization ◽  
Bond Formation ◽  
Transition Metal Catalysis ◽  
Metal Catalysis ◽  
Metal Free ◽  
Bond Forming ◽  
Intermolecular Cyclization

This review describes the progress of the last decade on the synthesis of substituted benzofurans, which are useful scaffolds for the synthesis of numerous natural products and pharmaceuticals. In particular, new intramolecular and intermolecular C–C and/or C–O bond-forming processes, with transition-metal catalysis or metal-free are summarized. (1) Introduction. (2) Ring generation via intramolecular cyclization. (2.1) C7a–O bond formation: (route a). (2.2) O–C2 bond formation: (route b). (2.3) C2–C3 bond formation: (route c). (2.4) C3–C3a bond formation: (route d). (3) Ring generation via intermolecular cyclization. (3.1) C7a-O and C3–C3a bond formation (route a + d). (3.2) O–C2 and C2–C3 bond formation: (route b + c). (3.3) O–C2 and C3–C3a bond formation: (route b + d). (4) Benzannulation. (5) Conclusion.

Fixation of sulfur dioxide into small molecules

2015 ◽  
Vol 13 (6) ◽  
pp. 1592-1599 ◽  
Author(s):  
Gang Liu ◽  
Congbin Fan ◽  
Jie Wu
Keyword(s):  
Sulfur Dioxide ◽  
Transition Metal ◽  
Small Molecules ◽  
Transition Metal Catalysis ◽  
Metal Catalysis ◽  
Radical Process ◽  
Metal Free ◽  
Recent Advances

Recent advances in the insertion of sulfur dioxide under transition metal catalysis or metal-free conditions via a radical process are presented.

scholarly journals Transition-Metal-Free Synthesis of Conjugated Microporous Polymers via Amine-Catalyzed Suzuki-Miyaura Coupling Reaction

2021 ◽  
Author(s):  
Qingmin Liu ◽  
Shangbin Jin ◽  
Bien Tan
Keyword(s):  
Transition Metal ◽  
Noble Metal ◽  
Coupling Reaction ◽  
Transition Metal Catalysis ◽  
Coupling Reactions ◽  
Metal Catalysis ◽  
Metal Free ◽  
Noble Metal Catalysts ◽  
Microporous Polymers ◽  
Conjugated Microporous Polymers

The synthesis of conjugated microporous polymers (CMPs) has been heavily relied on transition-metal-catalysis carbon-carbon coupling reactions, which has shortages in the scarcity and high cost of the noble metal catalysts....

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