Lewis Acid Mediated Domino Intramolecular Cyclization: Synthesis of Dihydrobenzo[<i>a</i>]fluorenes

Kishore, Dakoju Ravi; Shekhar, Chander; Satyanarayana, G.

doi:10.1021/acs.joc.1c00525

Cited by 11 publications

(12 citation statements)

References 33 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A plausible mechanism that is consistent with the aforementioned observations, the precedent work, 17,22 the density functional theory (DFT) calculation data 23 ■ EXPERIMENTAL SECTION General Remarks. Column chromatography was carried out on silica gel (200−300 mesh).…”

Section: ■ Results and Discussionsupporting

confidence: 68%

Dual Proton/Silver-Catalyzed Serial (5 + 2)-Cycloaddition and Nazarov Cyclization of (E)-2-Arylidene-3-hydroxyindanones with Conjugated Eneynes: Synthesis of Indanone-Fused Benzo[cd]azulenes

Zhu

Liang

et al. 2023

J. Org. Chem.

View full text Add to dashboard Cite

A one-pot step-economic tandem process involving (5 + 2)-cycloaddition and Nazarov cyclization reactions has been reported for the facile synthesis of indanone-fused benzo[cd]azulenes from (E)-2-arylidene-3-hydroxyindanones and conjugated eneynes. This highly regio-and stereoselective bisannulation reaction is enabled by dual silver and Brønsted acid catalysis and opens up a new avenue for the construction of important bicyclo[5.3.0]decane skeletons.

show abstract

Section: ■ Results and Discussionsupporting

confidence: 68%

Dual Proton/Silver-Catalyzed Serial (5 + 2)-Cycloaddition and Nazarov Cyclization of (E)-2-Arylidene-3-hydroxyindanones with Conjugated Eneynes: Synthesis of Indanone-Fused Benzo[cd]azulenes

Zhu

Liang

et al. 2023

J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…The optimization study is commenced by taking 2-(2-bromophenoxy)-1-phenylethan-1-one 3a and phenylacetylene 4a as exemplary substrates for accomplishing the target product (3-benzylbenzofuran-2-yl)(phenyl)methanone 5a . Initially, the reaction is performed with our previously reported Sonogashira conditions [Pd(OAc) 2 (3 mol %), PPh 3 (6 mol %), Cs 2 CO 3 (1.5 equiv) in DMF (1.5 mL) at 100 °C for 12 h] . However, the requisite product is not formed and leads to the decomposition of the starting material (Table , entry 1).…”

Section: Resultsmentioning

confidence: 99%

“…Initially, the reaction is performed with our previously reported Sonogashira conditions [Pd(OAc) 2 (3 mol %), PPh 3 (6 mol %), Cs 2 CO 3 (1.5 equiv) in DMF (1.5 mL) at 100 °C for 12 h]. 28 However, the requisite product is not formed and leads to the decomposition of the starting material (Table 1, entry 1). Indeed, it is worth mentioning that even the corresponding Sonogashira product was not observed.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Intermolecular Sonogashira Coupling and Intramolecular 5-Exo-dig Cycloisomerization Cascade: A One-Pot Pathway for Accessing (3-Benzylbenzofuran-2-yl)(phenyl)methanones

Kishore

Satyanarayana

2022

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

Herein, we present an efficient and straightforward strategy enabling access to 2,3-disubstituted benzo[b]furans. The whole synthetic process proceeds via a domino intermolecular Sonogashira coupling of 2-(2-bromophenoxy)-1-phenylethan-1-ones/alkyl 2-(2-bromophenoxy)acetates/2-(2-bromophenoxy)acetonitrile/1-(2-bromophenoxy)propan-2-one with terminal acetylenes followed by an intramolecular carbanion-yne cyclization in a 5-exo-dig manner and subsequent double-bond isomerization. Notably, two C–C bonds have been constructed in a one-pot manner and a wide variety of (3-benzylbenzofuran-2-yl)(phenyl)methanones were accomplished with good functional group tolerance.

show abstract

“…In this line, very recently, our group has demonstrated the synthesis of dihydrobenzo[ a ]fluorene derivatives via the intramolecular domino cyclization of alkynols by using a catalytic amount of BF 3 ·OEt 2 as shown in Scheme . Inspired by these results, herein, we present an intramolecular cascade cycloaromatization of ynones catalyzed by BF 3 ·OEt 2 , which affords the benzo[ a ]fluorene and benzo[ b ]fluorene derivatives with different substitution patterns.…”

Section: Introductionmentioning

confidence: 96%

An Access to Benzo[a]fluorenes, Benzo[b]fluorenes, and Indenes Triggered by Simple Lewis Acid

et al. 2022

Self Cite

View full text Add to dashboard Cite

This report illustrates BF 3 •OEt 2 promoted intramolecular cascade cycloaromatization of 1,7-ynones toward synthesizing structurally diverse benzofluorene scaffolds. Remarkably, the present protocol promotes the formation of two consecutive C−C bonds intramolecularly and undergoes aromatization under mild reaction conditions to afford the tetracyclic benzo[a]fluorene frameworks. Besides, the formation of indenes was observed when 1-bromo-2-iodoarenes are relatively more electron-rich when compared with the one originating from the terminal arylacetylenes, under controlled conditions, wherein triple bond polarity has been just reversed due to the change of electronic effects exerted by the strong +M group of 1-bromo-2iodoarenes, which is in conjugation to the connected triple bond. The same concept to generate indenes has also been extended by using aliphatic alkyne tethered ynones. Further, it was noticed that 1,7-ynones bearing the more electron-rich 1-bromo-2-iodoarenes than the arene ring arriving from the terminal arylacetylenes lead to benzo[b]fluorenes, under thermodynamic conditions, instead of delivering the benzo[a]fluorenes. In addition, this method features metal-free conditions, easily accessible starting materials, operational simplicity, gram-scale synthesis, and a wide range of substrate scopes.

show abstract

Lewis Acid Mediated Domino Intramolecular Cyclization: Synthesis of Dihydrobenzo[a]fluorenes

Cited by 11 publications

References 33 publications

Dual Proton/Silver-Catalyzed Serial (5 + 2)-Cycloaddition and Nazarov Cyclization of (E)-2-Arylidene-3-hydroxyindanones with Conjugated Eneynes: Synthesis of Indanone-Fused Benzo[cd]azulenes

Dual Proton/Silver-Catalyzed Serial (5 + 2)-Cycloaddition and Nazarov Cyclization of (E)-2-Arylidene-3-hydroxyindanones with Conjugated Eneynes: Synthesis of Indanone-Fused Benzo[cd]azulenes

Intermolecular Sonogashira Coupling and Intramolecular 5-Exo-dig Cycloisomerization Cascade: A One-Pot Pathway for Accessing (3-Benzylbenzofuran-2-yl)(phenyl)methanones

An Access to Benzo[a]fluorenes, Benzo[b]fluorenes, and Indenes Triggered by Simple Lewis Acid

Contact Info

Product

Resources

About