Palladium‐Catalyzed Synthesis of 2,3‐Disubstituted Benzofurans: An Approach Towards the Synthesis of Deuterium Labeled Compounds

Agasti, Soumitra; Maity, Soham; Szabó, Kálmán J.; Maiti, Debabrata

doi:10.1002/adsc.201500308

Cited by 43 publications

(13 citation statements)

References 81 publications

(30 reference statements)

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“…3-Phenyl benzofurans possess antimicrobial and antifungal activities and also act as pharmacological molecular switches for K + and Cl – channels . Synthesis of 3-phenylbenzofurans involved multisteps from ortho -hydroxy acetophenone involving the use of PhMgBr, followed by cyclization in the presence of CuI and Pd catalysts. , Here, 3-phenyl benzofurans 48 and 49 were obtained from 2-(2-bromo-4-nitrophenyl)-acetamides 2 and 16 in 62% and 65% yields under TM-free conditions.…”

Section: Results and Discussionmentioning

confidence: 99%

Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp³ and sp² C–H Bonds

et al. 2016

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A chemo- and regioselective intermolecular sp C-H and sp C-H coupling reaction for C-C bond formation is described to access unsymmetrical diaryl acetamides under TM-free conditions from sec- and tert-arylacetamides and nitroarenes using tert-butoxide base in DMSO at room temperature. The coupling partners with sensitive functionalities such as chloro, bromo, hydroxy, and cyano were also amenable to the developed reaction. Synthesized α-(2/4-nitroaryl) phenylacetamides have been transformed into biologically important benzofurans, xanthenes, diaryl indoles, and unsymmetrical benzophenones by novel routes without applying a transition metal. Overall, an economical, yet efficient, strategy has been devised to access unsymmetrical diarylacetamides with the possibility of their further elaboration into a variety of biologically important heterocycles. Mechanistic understanding suggests that the reaction proceeds by a nucleophilic addition of a phenylacetamide carbanion, which is generated in the presence of tert-butoxide base, to the para or ortho (if para is substituted) position of nitrobenzene. The formed α-(4-nitrocyclohexa-2,4-dien-1-yl) phenylacetamide anion intermediate oxidized by a basic solution of DMSO or atmospheric oxygen led to the desired sp C-H and sp C-H coupled α-(2/4-nitroaryl) phenylacetamides.

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Section: Results and Discussionmentioning

confidence: 99%

Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp³ and sp² C–H Bonds

et al. 2016

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“…75,76 Further, simultaneous functionalizations at 2-and 3-positions of benzofuran were also realized. 28 Rovis and Neely reported similar selectivity inversion in the synthesis of 2-and 3-substituted pyridines (Scheme 2). 29,30 Seemingly, the selection of olefinic partners is critical to the selectivity inversion and can be implemented for the generation of diverse core structures.…”

Section: ■ Introductionmentioning

confidence: 77%

Mechanistic Insights on Orthogonal Selectivity in Heterocycle Synthesis

2018

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Recently, we have developed a method for catalytic regioselective synthesis of 2-substituted and 3-substituted benzofurans starting from phenols. The choice of reacting partner, olefin versus α,β-unsaturated acid, is critical to dictate the isomeric product formation. Instances are known where these olefinic partners did not complement each other and yield a similar outcome. In the current work, we have addressed this paradox with emphasis on (a) the origin of orthogonal selectivity and (b) the key requirements to expect complementary behavior. Experimental and computational studies provided important mechanistic insights. Electrostatic compatibility during migratory insertion and the positioning of the carboxylic acid moiety in catalytic steps are found to exert a paramount impact in determining the regioselectivity. The study offers a predictable single component tuning tool to control the regioselectivity.

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“…The products from this approach underwent subsequent functionalization, to gain Palladium-catalyzed oxidative annulations between phenols and alkenylcarboxylic acids produced a library of benzofuran compounds. Depending on the nature of the substitution of the phenol precursor, either 2,3-dialkylbenzofurans or 2-alkyl-3-methylene-2,3-dihydrobenzofurans were synthesized with excellent regioselectivity [38,[171][172][173].…”

Section: Via Interrupted Pummerer Reaction/[33] Sigmatropic Rearrangement/cyclizationmentioning

confidence: 99%

Last Decade of Unconventional Methodologies for the Synthesis of Substituted Benzofurans

Chiummiento¹,

D’Orsi²,

Funicello³

et al. 2020

Molecules

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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.

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Palladium‐Catalyzed Synthesis of 2,3‐Disubstituted Benzofurans: An Approach Towards the Synthesis of Deuterium Labeled Compounds

Cited by 43 publications

References 81 publications

Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp³ and sp² C–H Bonds

Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp³ and sp² C–H Bonds

Mechanistic Insights on Orthogonal Selectivity in Heterocycle Synthesis

Last Decade of Unconventional Methodologies for the Synthesis of Substituted Benzofurans

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Palladium‐Catalyzed Synthesis of 2,3‐Disubstituted Benzofurans: An Approach Towards the Synthesis of Deuterium Labeled Compounds

Cited by 43 publications

References 81 publications

Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp3 and sp2 C–H Bonds

Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp3 and sp2 C–H Bonds

Mechanistic Insights on Orthogonal Selectivity in Heterocycle Synthesis

Last Decade of Unconventional Methodologies for the Synthesis of Substituted Benzofurans

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Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp³ and sp² C–H Bonds

Synthesis of Unsymmetrical Diaryl Acetamides, Benzofurans, Benzophenones, and Xanthenes by Transition-Metal-Free Oxidative Cross-Coupling of sp³ and sp² C–H Bonds