The structure and absolute configuration of viridicatumtoxin: 2'S-(2'α,7'aβ,11'aβ,12'β)-7',7'a,8',11',11'a,12'-hexahydro-5',6',7'a,10',11'a,12'-hexahydroxy-3'-methoxy-2,6,6-trimethyl-7',8'-dioxospiro[2-cyclohexene-1,2'(1'H)-cyclopenta[de]naphthacene]-9'-carboxamide methanolate

Silverton, J. V.; Kabuto, Chizuko; Akiyama, Toshihiko

doi:10.1107/s0567740882010759

Cited by 9 publications

(17 citation statements)

References 5 publications

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“…Class Pattern HB1 HB2 al., 1992; de C. T. Carrondo et al, 1994;Clegg & Teat, 2000;Mukhopadhyaya et al, 2000a) and in 18 cases to the second tautomer (2.Vb; 3.Vb,b 0 0 0 ,b 0 0 0 0 ) (Von Dreele & Hughes, 1971;Stezowski, 1976;Palenik et al, 1978;Kollat & Stezowski, 1982;Silverton et al, 1982;Ried et al, 1985;Bossio et al, 1993;Ozturk et al, 1998;Shishkina et al, 2000;Ukrainets, Taran, Likhanova, Amin & Shishkin, 2000;Ukrainets, Taran, Likhanova, Rybakov et al, 2000;Mukhopadhyaya et al, 2000b). The third non-tautomeric isomer [2,3 0 ]OONO (2.Vc) was observed only once (Wiley et al, 1986).…”

Section: Data Retrievalmentioning

confidence: 99%

π-Bond cooperativity and anticooperativity effects in resonance-assisted hydrogen bonds (RAHBs)

Bertolasi

Pretto

Gilli

et al. 2006

Acta Crystallogr B Struct Sci

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Bond cooperativity effects, which are typical of ;resonant' chains or rings of pi-conjugated hydrocarbons, can also occur in hydrogen-bonded systems in the form of sigma-bond and pi-bond cooperativity or anticooperativity. sigma-Bond cooperativity is associated with the long chains of O-H...O bonds in water and alcohols while sigma-bond anticooperativity occurs when the cooperative chain is interrupted by a local defect reversing the bond polarity. pi-Bond cooperativity is the driving force controlling resonance-assisted hydrogen bonds (RAHBs), while pi-bond anticooperativity has never been considered so far and is investigated here by studying couples of hydrogen-bonded beta-enolone and/or beta-enaminone six-membered rings fused through a common C=O or C-C bond. The effect is studied by X-ray crystal structure determination of five compounds [(2Z)-1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione enol (1), (2Z)-1-(2-hydroxy-5-chlorophenyl)-3-phenyl-1,3-propanedione enol (2), (2Z)-1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione enol (3), (2Z)-1-(2-hydroxy-4-methyl-5-chlorophenyl)-3-phenyl-1,3-propanedione enol (4) and dimethyl(2E)-3-hydroxy-2-{[(4-chlorophenyl)amino]carbonyl}pent-2-enedioate (5)] and by extensive analysis of related fragments found in the CSD (Cambridge Structural Database). It is shown that fusion through the C=O bond is always anticooperative and such to weaken the symmetric O-H...O...H-O and N-H...O...H-N bonds formed, but not the asymmetric O-H...O...H-N bond. Fusion through the C-C bond may produce either cooperative or anticooperative hydrogen bonds, the former being more stable than the latter and giving rise to a unique resonance-assisted ten-membered ring running all around the two fused six-membered rings, which can be considered a type of tautomerism never described before.

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Section: Data Retrievalmentioning

confidence: 99%

π-Bond cooperativity and anticooperativity effects in resonance-assisted hydrogen bonds (RAHBs)

Bertolasi

Pretto

Gilli

et al. 2006

Acta Crystallogr B Struct Sci

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“…The antibacterial activity of 1 against S. aureus, MRSA, and [3]. The absolute configuration of viridicatumtoxin has been determined by X-ray crystallographic methods [5]. The absolute configuration of compound 1 was not determined in this study because of a small amount.…”

Section: Structure Elucidationmentioning

confidence: 99%

Viridicatumtoxin B, a new anti-MRSA agent from Penicillium sp. FR11

Zheng

Kim

et al. 2008

J Antibiot

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A new tetracycline-type antibiotic named viridicatumtoxin B along with the known compound viridicatumtoxin has been isolated from the mycelium of liquid fermentation cultures of Penicillium sp. FR11. The structure of viridicatumtoxin B was determined on the basis of MS and NMR data. Viridicatumtoxin B inhibited the growth of Staphylococcus aureus including methicillinresistant S. aureus and quinolone-resistant S. aureus with MIC (m g/ml) of 0.5, which is similar with that of vancomycin, but 8ϳ64 times higher activity than that of tetracycline.

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“…Having developed an efficient and highly enantioselective synthesis of 10-substituted anthrones, we were in a position to undertake the total synthesis of enantiopure viridicatumtoxin B in an attempt to determine its absolute configuration. Given that the literature reports on the structures of viridicatumtoxin A ( 2 , Figure ; absolute configuration confirmed by X-ray crystallographic analysis) and spirohexaline ( 3 , reported structure shown in Figure ) suggested opposite absolute configurations for these two siblings, we were ambivalent as to which absolute configuration of viridicatumtoxin B to target first. Since our asymmetric synthesis of anthrones revealed a higher diastereoselectivity for PTC15 (leading to the corresponding C10-substituted anthrones, see Table ) than that for PTC16 (leading to the antipodal enantiomer), we decided to employ the former as a means to reach one of the enantiomers of viridicatumtoxin B ( 1 ).…”

Section: Resultsmentioning

confidence: 85%

“…In view of the importance and recent emphasis on new antibacterial agents to combat dangerous bacterial infections, we sought to develop a general asymmetric synthesis of members of this family of compounds that includes, in addition to viridicatumtoxins B ( 1 ) and A ( 2 ), spirohexaline ( 3 , Figure ). Interestingly, the latter compound was depicted in the original publication as shown in structure 3 despite its antipodal nature to that of its closest relative 2 , whose absolute configuration was determined by X-ray crystallographic analysis . This puzzling difference heightened the intrigue over the absolute configuration of viridicatumtoxin B ( 1 ).…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Alkylation of Anthrones, Enantioselective Total Synthesis of (−)- and (+)-Viridicatumtoxins B and Analogues Thereof: Absolute Configuration and Potent Antibacterial Agents

et al. 2017

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A phase transfer catalyzed asymmetric alkylation of anthrones with cyclic allylic bromides using quinidine- or quinine-derived catalysts is described. Utilizing mild basic conditions and as low as 0.5 mol % catalyst loading, and achieving up to >99:1 dr selectivity, this asymmetric reaction was successfully applied to produce enantioselectively (−)- and (+)-viridicatumtoxins B, and thus allowed assignment of the absolute configuration of this naturally occurring antibiotic. While the developed asymmetric synthesis of C10 substituted anthrones is anticipated to find wider applications in organic synthesis, its immediate application to the construction of a variety of designed enantiopure analogues of viridicatumtoxin B led to the discovery of highly potent, yet simpler analogues of the molecule. These studies are expected to facilitate drug discovery and development efforts toward new antibacterial agents.

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The structure and absolute configuration of viridicatumtoxin: 2'S-(2'α,7'aβ,11'aβ,12'β)-7',7'a,8',11',11'a,12'-hexahydro-5',6',7'a,10',11'a,12'-hexahydroxy-3'-methoxy-2,6,6-trimethyl-7',8'-dioxospiro[2-cyclohexene-1,2'(1'H)-cyclopenta[de]naphthacene]-9'-carboxamide methanolate

Cited by 9 publications

References 5 publications

π-Bond cooperativity and anticooperativity effects in resonance-assisted hydrogen bonds (RAHBs)

π-Bond cooperativity and anticooperativity effects in resonance-assisted hydrogen bonds (RAHBs)

Viridicatumtoxin B, a new anti-MRSA agent from Penicillium sp. FR11

Asymmetric Alkylation of Anthrones, Enantioselective Total Synthesis of (−)- and (+)-Viridicatumtoxins B and Analogues Thereof: Absolute Configuration and Potent Antibacterial Agents

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