A novel approach to the synthesis of benzo[b]fluoren-11-ones

Martı́nez, Ana M.; Barcia, José C.; Fernández, Fernando; González, Lucı́a; Estévez, Juan C.; Estévez, Ramón J.

doi:10.1016/j.tetlet.2007.01.112

Cited by 9 publications

(3 citation statements)

References 19 publications

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“…The conditions screened for aromatization included treatment of the starting α‐methylene ketone 22a with various oxidation catalysts. These conditions were 1) PIDA, MeCN, 12 h, room temperature, 2) TFA, CH 2 Cl 2 , 12 h, room temperature, 3) t BuOK, DMSO, 12 h, room temperature,43 4) RuCl 3 , EtOH, 24 h, reflux, 5) DDQ, dioxane, 24 h, reflux, 6) trimethylphenol, TFA, 90 °C, 24 h,44 7) MnO 2 (5 equiv. ), CH 2 Cl 2 , 48 h, room temperature, 8) Ag 2 O (5 equiv.…”

Section: Resultsmentioning

confidence: 99%

A Platform of Regioselective Methodologies to Access Polysubstituted 2‐Methyl‐1,4‐naphthoquinone Derivatives: Scope and Limitations

Rodo¹,

Feng²,

Jida³

et al. 2016

Eur J Org Chem

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A platform of synthetic methodologies has been established to access a focused library of polysubstituted 3‐benzylmenadione derivatives functionalized on the aromatic ring of the naphthoquinone core. Two main routes were explored: 1) The naphthol route, starting from either an α‐tetralone or a propiophenone, and 2) the regioselective Diels–Alder reaction, starting from various dienes and two 2‐bromo‐5(or 6)‐methyl‐1,4‐benzoquinones. 6‐Substituted 2‐methylnaphthols were synthesized by using a xanthate‐mediated free‐radical addition/cyclization sequence for the construction of the 6‐substituted menadione subunit. Furthermore, an efficient and simple new pathway that allows the formation of 6‐ or 7‐substituted 3‐(substituted‐benzyl)menadione regioisomers from a common commercial scaffold has also been developed by the naphthol route, advantageous with regard to step economy. Our synthetic methodologies exemplified by 34 compounds have allowed structure–activity relationships to be deduced for use as the basis for the development of new antimalarial redox‐active polysubstituted benzylmenadione derivatives.

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Section: Resultsmentioning

confidence: 99%

A Platform of Regioselective Methodologies to Access Polysubstituted 2‐Methyl‐1,4‐naphthoquinone Derivatives: Scope and Limitations

Rodo¹,

Feng²,

Jida³

et al. 2016

Eur J Org Chem

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“…The regioselectivity during the construction of the benzo[b]fluorene tetracyclic carbon skeleton is not a trivial undertaking at all, and assembling certain substitution patterns remains a challenge [9]. The most common approaches towards benzo[b]fluorenone can be divided roughly into Friedel-Crafts-type closures of acyl derivatives [10] (Scheme 1, path a) or transition metal-catalyzed arylations (Scheme 1, path b) [11][12][13][14][15]. Another approach by Mal et al was based on ring contraction via the benzil-benzilic acid rearrangement of benzo[a]anthracene-5,6-diones [16].…”

Section: Introductionmentioning

confidence: 99%

A new approach towards synthesis of benzo[b]fluorene core

Bogdanov

2014

Maced. J. Chem. Chem. Eng.

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New approach towards synthesis of benzo[b]fluorene core is described. The model compound, 10-methoxy-11H-benzo[b]fluoren-11-one was prepared in five steps starting from dibenzylmalonic acid. The key step was the metal catalyzed rearrangement of 3,3’-dihalo-2,2’-spirobiindan-1,1’-dione. The choice and proper activation of the metal was critical for the assembly of the benzo[b]fluorenone system. The zinc mediated rearrangement of the corresponding dibromo derivative led to the 10-hydroxy-11H-benzo[b]fluoren-11-one derivative in 52% yield. The structure of the product was established by spectroscopic methods and was additionally confirmed by standard methylation reaction to the 10-methoxy derivative, which is known in the literature.

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“…7,8 Taking into account that natural polyketides are restricted to a β-oxygenation pattern, [9][10][11] we anticipated that noncanonical 12 polyketide cyclisations governed by small-molecule catalysts would furnish valuable tetra-ortho-substituted atropisomeric biaryls distinct from dimerisation products. Considering the findings of stoichiometric biomimetic polyketide cyclisations, [13][14][15][16][17][18] we hence conceived a stereoselective polyketide cyclisation by means of catalytic substrate activation. More specifically, the controlled polyketide folding of substrate 2, characterised by a noncanonical oxygenation pattern (≠ β) obtained by an oxidative olefin cleavage of biindene 1, would directly give rise to atropisomeric binaphthalenes 4 by virtue of a twofold arene-forming aldol condensation (Fig.…”

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confidence: 99%

Atroposelective synthesis of tetra-ortho-substituted biaryls by catalyst-controlled non-canonical polyketide cyclizations

et al. 2019

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The cyclisation of poly-β-carbonyl-substrates controlled by polyketide synthases intricately governs the biosynthesis of a wide range of aromatic polyketides. Analogous small-molecule catalysed processes would conceivably induce selective cyclisations of noncanonical polycarbonyl substrates to provide products distinct from natural polyketides. Herein, we report a secondary amine-catalysed twofold cyclisation of noncanonical hexacarbonyl substrates furnishing enantioenriched tetra-ortho-substituted binaphthalenes. The substrates were prepared by a fourfold ozonolysis of dicinnamyl biindenes and converted under catalyst-control with high atroposelectivity. Privileged catalysts and ligands were readily accessible from the binaphthalene products stemming from the noncanonical polyketide cyclisations.Poly-β-carbonyl chains, assembled by nonreducing polyketide synthases from acetate units, are biosynthetically diverged into a myriad of aromatic natural products. In particular their selective folding, aldol cyclisation and ensuing dehydration result in a broad range of skeletal variation, while tailoring steps further extend the diversity of the polyketide architecture (Fig. 1a). 1-3 Moreover, subsequent enzymatic dimerisations provide structurally markedly unique atropisomeric scaffolds, typically with control over the configuration of stereogenic axes. [4][5][6] Whereas the radical intermediates of dimerisation processes set the basis of biomimetic strategies, they also dictate the regioselectivity for ortho-and para-phenol couplings. 7,8 Taking into account that natural polyketides are restricted to a β-oxygenation pattern, [9][10][11] we anticipated that noncanonical 12 polyketide cyclisations governed by small-molecule catalysts would furnish valuable tetra-ortho-substituted atropisomeric biaryls distinct from dimerisation products. Considering the findings of stoichiometric biomimetic polyketide cyclisations, [13][14][15][16][17][18] we hence conceived a stereoselective polyketide cyclisation by means of catalytic substrate activation. More specifically, the controlled polyketide folding of substrate 2, characterised by a noncanonical oxygenation pattern (≠ β) obtained by an oxidative olefin cleavage of biindene 1, would directly give rise to atropisomeric binaphthalenes 4 by virtue of a twofold arene-forming aldol condensation (Fig. 1b, 2→4).

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A novel approach to the synthesis of benzo[b]fluoren-11-ones

Cited by 9 publications

References 19 publications

A Platform of Regioselective Methodologies to Access Polysubstituted 2‐Methyl‐1,4‐naphthoquinone Derivatives: Scope and Limitations

A Platform of Regioselective Methodologies to Access Polysubstituted 2‐Methyl‐1,4‐naphthoquinone Derivatives: Scope and Limitations

A new approach towards synthesis of benzo[b]fluorene core

Atroposelective synthesis of tetra-ortho-substituted biaryls by catalyst-controlled non-canonical polyketide cyclizations

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