- Synthesis of stentorin
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The two symmetrical structures 1 and 2 proposed for the photodynamic pigment stentorin have both been synthesised, thereby establishing the correctness of structure 1.
- Cameron, Donald W.,Riches, Andrew G.
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- Approach to the synthesis of steffimycins. Preparation and antibacterial activity of (±) 8-demethoxy 7-epi (?) steffimycinone
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Title compound has been prepared in five steps from the readily available 3-chloro 5-hydroxy 7-methoxy 1,4-naphthoquinone, and tested for antibacterial activity.
- Gesson,Jacquesy,Renoux
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- First total synthesis of topopyrone C
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The first synthesis of topopyrone C, a natural compound and inhibitor of Topoisomerase I, has been carried out by Marschalk alkylation of 1-hydroxy-3,6,8-trimethoxyanthraquinone, followed by a Baker-Venkataraman chain elongation and an acid-catalyzed cyclization for the construction of the pyrone ring.
- Gattinoni, Sonia,Merlini, Lucio,Dallavalle, Sabrina
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- A biocatalytic approach towards the preparation of natural deoxyanthraquinones and their impact on cellular viability
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Herein, a two-step chemoenzymatic process for the synthesis of medicinally important 3-deoxygenated anthra-9,10-quinones is developed. It involves a regio- and stereoselective reduction of hydroanthraquinones to (R)-configured dihydroanthracenones using an anthrol reductase of T. islandicus, followed by oxidation and dehydration to obtain deoxyanthraquinones in 65-80% yield. Comparison of the cell viability of normal human kidney HEK293 cells between anthraquinones and their deoxy derivatives revealed less toxicity for the latter.
- Das, Kiran,De, Arijit,Husain, Syed Masood,Maity, Biswanath,Mondal, Amit,Rajput, Anshul
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supporting information
p. 3087 - 3090
(2022/02/21)
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- Synthesis of (-)-Flavoskyrins by Catalyst-Free Oxidation of (R)-Configured Dihydroanthracenones in Aqueous Media and Its (Bio)synthetic Implications
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A catalyst-free method for the synthesis of dimeric (-)-flavoskyrins has been developed. It involves the autoxidation of chemoenzymatically synthesized (R)-configured dihydroanthracenones in the presence of molecular oxygen in buffer of pH 6.0 followed by spontaneous [4 + 2] cycloaddition in stereocontrolled exo-anti fashion to form (-)-flavoskyrins. The method is applied to obtain several homo- A s well as heterodimerized flavoskyrins (nine examples) in 27-72% yield and implies the involvement of a similar pathway in the (bio)synthesis of modified bisanthraquinones and their analogues.
- Mondal, Amit,De, Arijit,Husain, Syed Masood
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supporting information
p. 8511 - 8515
(2020/11/12)
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- Identification and characterization of an anthrol reductase from: Talaromyces islandicus (Penicillium islandicum) WF-38-12
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An NADPH-dependent oxidoreductase from Talaromyces islandicus WF-38-12 has been identified through genome analysis. It has been shown to catalyze a regio- and stereoselective reduction of anthrols (formed in situ by the reduction of anthraquinones in the presence of Na2S2O4) to (R)-dihydroanthracenones, with high enantiomeric excess (>99%). The implications of results on the biosynthesis of deoxygenated (bis)anthraquinones and modified (bis)anthraquinones are discussed.
- Singh, Shailesh Kumar,Mondal, Amit,Saha, Nirmal,Husain, Syed Masood
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supporting information
p. 6594 - 6599
(2019/12/26)
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- Monomeric Dihydroanthraquinones: A Chemoenzymatic Approach and its (Bio)synthetic Implications for Bisanthraquinones
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Modified bisanthraquinones are complex dimeric natural products containing a cage-like structural motif. For their biosynthesis, monomeric dihydroanthraquinones have been proposed as key intermediates despite not being isolated from natural sources or synthesized as of yet. Here, isolation and characterization of dihydroemodin, as well as dihydrolunatin, synthesized by a biomimetic and chemoenzymatic approach using NADPH-dependent polyhydroxyanthracence reductase (PHAR) from Cochliobolus lunatus followed by Pb(OAc)4 oxidation is reported. Subsequent dimerization through a hetero-Diels–Alder reaction of the dihydroemodin and dihydrolunatin resulted in (?)-flavoskyrin (68 %) and (?)-lunaskyrin (62 %), respectively. Pyridine treatment of (?)-flavoskyrin and (?)-lunaskyrin gave (?)-rugulosin and (?)-2,2′-epi-cytoskyrin A in 64 % and 60 % yield, respectively, through a cascade that involves two dimeric intermediates. Implications of the described synthesis for the biosynthesis of bisanthraquinones by a combination of enzymatic and spontaneous steps are discussed.
- Saha, Nirmal,Mondal, Amit,Witte, Karina,Singh, Shailesh Kumar,Müller, Michael,Husain, Syed Masood
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supporting information
p. 1283 - 1286
(2018/01/27)
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- First enantioselective total synthesis of altersolanol A
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The first enantioselective total synthesis of altersolanol A, a secondary metabolite from the endophytic fungi Stemphylium globuliferum and Alternaria solani, is described. The key step towards the tetrahydroanthraquinone core was an asymmetric Diels-Alder (D-A) cycloaddition promoted by (R)-3,3′-diphenyl-BINOL/boron Lewis acid with good to excellent yields and excellent diastereo- and enantioselectivity (>95 : 5 dr and 98 : 2 er).
- Mechsner, Bastian,Hen?en, Birgit,Pietruszka, J?rg
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supporting information
p. 7674 - 7681
(2018/11/02)
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- Total synthesis of 1-hydroxydehydroherbarin and ascomycones A, B, naphthoquinone antibiotics
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The first total synthesis of 1-hydroxydehydroherbarin and ascomycones A and B is reported. The biologically interesting ascomycones A and B were obtained in 18percent overall yield starting from 3-chloro-2,5-dimethoxybenzaldehyde as building block.
- Dong, Wen-Kai,Huang, Xiong,Xu, Dong-Cheng,Lia, Xin-Sheng,Xie, Jian-Wu
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scheme or table
p. 280 - 284
(2012/06/01)
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- Total synthesis of the topopyrones: A new class of topoisomerase I poisons
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(Chemical Equation Presented) The topopyrones represent a new class of highly cytotoxic topoisomerase I poisons. Efficient total syntheses of all four naturally occurring members of this class have been accomplished. Key elements of the syntheses include Diels-Alder reactions employing two novel dienes and a titanium-mediated ortho-directed Friedel-Crafts acylation. Additionally, the syntheses of two chlorinated analogues accessible from an advanced intermediate are described.
- Elban, Mark A.,Hecht, Sidney M.
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p. 785 - 793
(2008/09/18)
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- Synthesis of stentorin
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The two isomeric structures (2) and (3) proposed for the photodynamic pigment stentorin have both been synthesized for the first time, thereby allowing unambiguous identification of the natural material as (2). Synthesis of these highly condensed aromatic systems involved controlled oxidative couplings of the new anthrones (7) and (8), each synthesized by regiocontrolled cycloaddition.
- Cameron, Donald W.,Riches, Andrew G.
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p. 409 - 424
(2007/10/03)
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- REACTIONS OF KETENE ACETALS-14; THE USE OF SIMPLE MIXED VINYLKETENE ACETALS IN THE ANNULATION OF QUINONES
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α,β- and β,γ-unsaturated esters can be converted by strong base and chlorotrimethylsilane to the corresponding mixed vinylketene acetals which are shown to be particularly useful and generally applicable reagents for the regiospecific annulation of halogenoquinones.The reaction proceeds readily with a variety of substrates including benzoquinones.
- Savard, Jacques,Brassard, Paul
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p. 3455 - 3464
(2007/10/02)
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