Palladium‐Catalyzed Synthesis of Benzofurans and Coumarins from Phenols and Olefins

Sharma, Upendra; Naveen, Togati; Maji, Arun; Manna, Srimanta; Maiti, Debabrata

doi:10.1002/ange.201305326

Cited by 63 publications

(22 citation statements)

References 132 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While 9b is generated from 1a , in the Pd(II)‐mediated catalytic cycle, Pd(II) phenolate 10 and AcOH are generated from a ligand exchange process 21. The likely pathway for the formatiom of Pd(II) phenolate from phenol and Pd(OAc) 2 has been already described in the literature 22. The reaction between 10 and 9b catalyzed by AcOH (or directly with 9a ) leads to a penultimate intermediate 11 and a molecule of TBHP.…”

Section: Resultsmentioning

confidence: 87%

“…[21] The likely pathway for the formatiom of Pd(II) phenolate from phenol and Pd-A C H T U N G T R E N N U N G (OAc) 2 has been already described in the literature. [22] The reaction between 10 and 9b catalyzed by AcOH (or directly with 9a) leads to a penultimate intermediate 11 and a molecule of TBHP. Tautomerization-induced ligand exchange from 11 will regenerate PdA C H T U N G T R E N N U N G (OAc) 2 and final product 3.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Direct Oxidative Arylation of C(sp³)H Bonds Adjacent to Oxygen of Ethers and Alcohols

Pandit

Lee

2014

Adv Synth Catal

View full text Add to dashboard Cite

OTf) 2 ]-catalyzed cross-dehydrgenative coupling in the presence of tert-butyl hyroperoxide (TBHP). This process provides exclusive installation of a tetrahydrofuranyl moiety at a more hindered position of multiply sub-stituted phenol derivatives. The cross-dehydrogenative coupling of 1,4-dihydroxynaphthalene with cyclic ethers and free alcohols afforded biologically interesting 2-substituted 1,4-naphthoquinone derivatives.

show abstract

Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Direct Oxidative Arylation of C(sp³)H Bonds Adjacent to Oxygen of Ethers and Alcohols

Pandit

Lee

2014

Adv Synth Catal

View full text Add to dashboard Cite

show abstract

“…[21,22] Thei mportance of this para-olefination method was further established by postsynthetic modifications of both the phenol and olefin core.B ym aking use of the phenolic hydroxy group, 5 was converted into benzofuran 14 and coumarin 23 (Scheme 5). [23] AC ÀOc oupling yielded derivative 15. [16] Alternatively,the phenolic hydroxy group could be transformed into as ynthetically useful triflate group in excellent yield, enabling subsequent Suzuki, Sonogashira, and C À Nc ouplings (17)(18)(19).…”

Section: Angewandte Chemiementioning

confidence: 99%

ChemInform Abstract: Palladium‐Catalyzed Directed para C—H Functionalization of Phenols.

et al. 2016

Self Cite

View full text Add to dashboard Cite

Various practical methods for the selective C À H functionalization of the ortho and recently also of the meta position of an arene have already been developed. Following our recent development of the directing-group-assisted para CÀHfunctionalization of toluene derivatives,weherein report the first remote para CÀHf unctionalization of phenol derivatives by using ar ecyclable silicon-containing biphenylbased template.The effectiveness of this strategy was illustrated with different synthetic elaborations and by the synthesis of various phenol-based natural products.Recent years have witnessed the emergence of CÀH activation as an effective method for the synthesis of complex molecules.[1] As evident from several examples in nature, chemical transformations that involve the functionalization of C À Hbonds are coined to be efficient when they proceed with ac ommendable degree of selectivity. [2][3][4][5] One strategy for ensuring ahighly selective functionalization entails the use of ad irecting group.[6] This approach has been significantly exploited in the last two decades to selectively activate the ortho [7] and more recently the meta C À Hb onds [8,9] of arenes containing multiple C À Hb onds with very similar intrinsic reactivity.H owever,t he effective employment of such as trategy for the selective activation of a para CÀHb ond has remained extremely difficult. This was attributed to the problems associated with forming al arge cyclophane-like metallacycle,w hich is required for the functionalization of aC À Hb ond situated far away from the coordinating functional group.T he need for an optimum chain length poses afurther impediment towards devising atemplate that would enable the facilitated delivery of the electrophile through aw eakly coordinating donor group.O vercoming these challenges,o ur group recently reported the first templatedirected para C À Hfunctionalization of toluene derivatives. [10] To date,C À Hactivation reactions with phenol derivatives have predominantly occurred at the ortho and meta position in the presence of as uitable template, [11,12] or selectivity was based exclusively on steric and electronic bias. [5,13] The directing-group-assisted para-selective functionalization of such am olecule would effectively overrule its vulnerability towards electrophilic attack at both the 2-and 4-position (Scheme 1a).Following our previous report [10] and in order to optimize the template design, abiphenyl moiety was employed as part of the template chain along with as ilicon center with two bulky isopropyl groups as the ligation center (Scheme 1b, S1).[14] Switching the connecting carbon and oxygen atoms in our previous template led to am odified system for the para C À Hfunctionalization of phenol. [15] This modification ensures that the donor nitrile group will be placed at ap osition suitable for the formation of the desired metallacycle in the transition state.T he end-on coordination by the directing moiety leads to as uitable placement of the weakly held electrophile through th...

show abstract

“…[ 6 ] Recently, we have contributed to this area by synthesizing a wide array of 2-substituted benzofurans through a unique Pd-catalyzed annulation of simple phenols and olefins. [ 7 ] Of more interest was an orthogonal approach with cinnamic acids, which gave rise to 3-substituted benzofurans with excellent selectivity. [ 8 ] In this context, we became interested in the prospect of synthesizing 2,3-disubstituted benzofuran derivatives starting from phenols.…”

mentioning

confidence: 99%

“…[ 8 ],[ 23 ] In the presence of palladium, intermediate I will cyclize to form Int - II , which is the key species for the formation of 3 and 4 . [ 1b ],[ 7 ],[ 11c ] Syn β-hydride elimination from intermediate II leads to the formation of the desired benzofuran products and regenerates the Pd(0) species. [ 7 ] This Pd(0) is readily oxidised to Pd(II) by Cu(OAc) 2 ⋅H 2 O under an oxygen atmosphere to maintain the catalytic process.…”

mentioning

confidence: 99%

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

et al. 2015

Self Cite

View full text Add to dashboard Cite

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 can be synthesized with excellent regioselectivity. Reactions between conjugated 5-phenylpenta-2,4-dienoic acids and phenol gave 3-alkylidenedihydrobenzofuran alkaloid motifs while biologically active 7-arylbenzofuran derivatives were prepared by starting from 2-phenylphenols. More interestingly, selective incorporation of deuterium from D2O has been discovered, which offers an attractive one-step method to access deuterated compounds.

show abstract

Palladium‐Catalyzed Synthesis of Benzofurans and Coumarins from Phenols and Olefins

Abstract: Dreifache C‐H‐Funktionalisierung: Die mit einer Reihe von Funktionalitäten vereinbare Titelreaktion verknüpft Phenole und nichtaktivierte Olefine über eine Folge von C‐H‐Funktionalisierungen. Auf der Grundlage erster Studien werden mögliche Reaktionsmechanismen diskutiert.

Cited by 63 publications

References 132 publications

Direct Oxidative Arylation of C(sp³)H Bonds Adjacent to Oxygen of Ethers and Alcohols

Direct Oxidative Arylation of C(sp³)H Bonds Adjacent to Oxygen of Ethers and Alcohols

ChemInform Abstract: Palladium‐Catalyzed Directed para C—H Functionalization of Phenols.

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

Contact Info

Product

Resources

About

Palladium‐Catalyzed Synthesis of Benzofurans and Coumarins from Phenols and Olefins

Abstract: Dreifache C‐H‐Funktionalisierung: Die mit einer Reihe von Funktionalitäten vereinbare Titelreaktion verknüpft Phenole und nichtaktivierte Olefine über eine Folge von C‐H‐Funktionalisierungen. Auf der Grundlage erster Studien werden mögliche Reaktionsmechanismen diskutiert.

Cited by 63 publications

References 132 publications

Direct Oxidative Arylation of C(sp3)H Bonds Adjacent to Oxygen of Ethers and Alcohols

Direct Oxidative Arylation of C(sp3)H Bonds Adjacent to Oxygen of Ethers and Alcohols

ChemInform Abstract: Palladium‐Catalyzed Directed para C—H Functionalization of Phenols.

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

Contact Info

Product

Resources

About

Direct Oxidative Arylation of C(sp³)H Bonds Adjacent to Oxygen of Ethers and Alcohols

Direct Oxidative Arylation of C(sp³)H Bonds Adjacent to Oxygen of Ethers and Alcohols