Visible‐Light‐Photocatalyzed Metal‐Free C–H Heteroarylation of Heteroarenes at Room Temperature: A Sustainable Synthesis of Biheteroaryls

Maity, Pintu; Kundu, Debasish; Ranu, Brindaban C.

doi:10.1002/ejoc.201500006

Cited by 66 publications

(36 citation statements)

References 89 publications

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“…tert- Butyl nitrite ( t -BuONO) is used as a diazotizing agent to generate diazonium salts transiently in situ. The reaction is catalysed by Eosin Y under irradiation with blue LEDs at room temperature ( Scheme 7 ) [ 48 ].…”

Section: Reviewmentioning

confidence: 99%

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

Bogdos¹,

Pinard²,

Murphy³

2018

Beilstein J. Org. Chem.

109

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The focus of this review is to provide an overview of the field of organocatalysed photoredox chemistry relevant to synthetic medicinal chemistry. Photoredox transformations have been shown to enable key transformations that are important to the pharmaceutical industry. This type of chemistry has also demonstrated a high degree of sustainability, especially when organic dyes can be employed in place of often toxic and environmentally damaging transition metals. The sections are arranged according to the general class of the presented reactions and the value of these methods to medicinal chemistry is considered. An overview of the general characteristics of the photocatalysts as well as some electrochemical data is presented. In addition, the general reaction mechanisms for organocatalysed photoredox transformations are discussed and some individual mechanistic considerations are highlighted in the text when appropriate.

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Section: Reviewmentioning

confidence: 99%

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

Bogdos¹,

Pinard²,

Murphy³

2018

Beilstein J. Org. Chem.

109

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“…2‐(2‐Nitrophenyl)thiophene (3e) : Reaction time (12 h); eluent, EtOAc/ n ‐hexane (5%); yield: 144 mg (70%); 1 H NMR (300 MHz, CDCl 3 ): δ =7.74 (dt, J= 8.0, 1.1 Hz, 1 H), 7.61–7.54 (m, 2 H), 7.51–7.39 (m, 2 H), 7.13–7.05 (m, 2 H); 13 C NMR (75 MHz, CDCl 3 ): δ =149.52, 137.20, 132.33, 131.97, 128.68, 128.40, 127.83, 127.24, 127.21, 123.89.…”

Section: Methodsmentioning

confidence: 99%

Iodine‐Catalyzed Synthesis of Chalcogenophenes by the Reaction of 1,3‐Dienyl Bromides and Potassium Selenocyanate/Potassium Sulfide (KSeCN/K₂S)

Maity

Ranu

2017

Adv Synth Catal

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Them ethodsa vailable for the synthesis of chalcogenophenes,i ng eneral, are associated with drawbacks of harsh conditions,u se of costly metals, broad applicability,t edious purification process and low yield. To avoid these drawbacks at ransition metal-free iodine-catalyzed reactiono fa ryl-susbstituted 1,3-dienyl bromides with potassiums elenocyanate/potassium sulfide (KSeCN/K 2 S) leading to the corresponding selenophenes and thiophenes has been developed. Iodine is relatively benign,l ess expensive andr eadilya vailable.S everal diversely substituteds elenophenes and thiophenes have been obtained by this procedure in high yields.U sing this procedure 2-(4-chlorophenyl)thiophene,akey inter-mediatef or the synthesis of am elanin concentrating hormone receptor ligand involved in the treatment of eating disorders,w eight gain, obesity,d epression and anxiety has been synthesized. Although the reaction is one-pot essentially it proceeds in two steps involving as elenocyanate/thiolate intermediatel eading to the selenophene/thiophene.T he simple operation, use of inexpensive reagents andametal-free process make this procedure more attractive for an easy access to substituted selenophenes andthiophenes. 1 HNMR (300 MHz, CDCl 3 ): d = 7.94 (d, J = 5.8 Hz, 1H), 7.67-7.57 (m, 2H), 7.29-7.20 (m, 1H), 7.20-7.12 (m, 1H), 6.95-6.84 (m, 2H), 3.83 (s,3 H); 13 CNMR (75 MHz, CDCl 3 ): d = 155.

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“…In 2015 Kundu, Ranu and co-worker expanded the applicability of the eosin Y photocatalyzed C-H arylation, showing that furan, thiophene and N-protected-pyrrole are able to react with heteroarylamines at room temperature through in situ diazotization with t-BuONO. 57 Under blue LED irradiation, pyridinyl-, quinolinyl-, and thiazolylamines gave the required C-2 arylated derivatives when reacted with furan or 2-methylfuran in DMSO for 2 h in the presence of 1.2 equiv of t-BuONO. Similar results were also obtained when thiophene or N-Boc-pyrrole were used as coupling partners (Table 11).…”

Section: Visible-light Mediated Arylationmentioning

confidence: 99%

“…The same protocol was successfully applied to the synthesis of several 2-alkynyl substituted heteroarenes (Table 12), 57 previously prepared through a multistep procedure. 58 (a) Y=O, R=H: 10 equiv; Y=O, R=Me: 5 equiv; Y=S, R=H: 5 equiv; Y_N-Boc, R=H: 2 equiv.…”

Section: Visible-light Mediated Arylationmentioning

confidence: 99%

“…Notably, the authors found that anilines can also be valid arylating agents under their reaction conditions (Table 13). 57 The photocatalytic C-H arylation proved to be compatible with a wide spectrum of functional groups, including carbon-halogen bonds that remained unaltered during the course of the coupling. (a) Y=O, R=H: 10 equiv; Y=O, R=Me: 5 equiv; Y=S, R=H: 5 equiv; Y_N-Boc, R=H: 2 equiv.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Real Metal-Free C–H Arylation of (Hetero)arenes: The Radical Way

Bellina¹

2021

Synthesis

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Synthetic methodologies involving the formation of carbon-carbon bonds from carbon-hydrogen bonds are of significant synthetic interest, both for efficiency in terms of atom economy and for their undeniable usefulness in late-stage functionalization approaches. Combining these aspects with being metal-free, the radical C-H intermolecular arylation procedures covered by this review represent a powerful green means for the synthesis of (hetero)biaryl systems. 1. Introduction 2. Arylation with arenediazonium salts and related derivatives 2.1. Ascorbic acid as reductant 2.2. Hydrazines as reductants 2.3. Gallic acid as reductant 2.4. Polyanilines as reductants 2.5. Chlorpromazine hydrochloride as reductant 2.6 Phenalenyl-based radicals as reductants 2.7 Electrolytic reduction of diazonium salts 2.8 Visible-light mediated arylation 3. Arylation with arylhydrazines: generation of aryl radicals using an oxidant 4. Arylation with diaryliodonium salts 5. Arylation with aryl halides 6. Conclusions

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Visible‐Light‐Photocatalyzed Metal‐Free C–H Heteroarylation of Heteroarenes at Room Temperature: A Sustainable Synthesis of Biheteroaryls

Cited by 66 publications

References 89 publications

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

Iodine‐Catalyzed Synthesis of Chalcogenophenes by the Reaction of 1,3‐Dienyl Bromides and Potassium Selenocyanate/Potassium Sulfide (KSeCN/K₂S)

Real Metal-Free C–H Arylation of (Hetero)arenes: The Radical Way

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Visible‐Light‐Photocatalyzed Metal‐Free C–H Heteroarylation of Heteroarenes at Room Temperature: A Sustainable Synthesis of Biheteroaryls

Cited by 66 publications

References 89 publications

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

Iodine‐Catalyzed Synthesis of Chalcogenophenes by the Reaction of 1,3‐Dienyl Bromides and Potassium Selenocyanate/Potassium Sulfide (KSeCN/K2S)

Real Metal-Free C–H Arylation of (Hetero)arenes: The Radical Way

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Iodine‐Catalyzed Synthesis of Chalcogenophenes by the Reaction of 1,3‐Dienyl Bromides and Potassium Selenocyanate/Potassium Sulfide (KSeCN/K₂S)