The structure of chaetoglobosin A: a novel use of quartet invariants

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

doi:10.1107/s0567740878003581

Cited by 22 publications

(24 citation statements)

References 9 publications

(12 reference statements)

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“…3 Interestingly, the latter compound was depicted in the original publication 3 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. 5 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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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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“…Originally isolated in 1973 from a Penicillium species, [5] viridicatumtoxin A ( 1 ) was structurally elucidated through the aid of an X-ray crystallographic analysis in 1976. [6] In 2008, Kim and coworkers reported the re-isolation of viridicatumtoxin A ( 1 ) as well as the isolation of viridicatumtoxin B, whose structure was assigned as 2 (Figure 1). [7] Finally, spirohexaline ( 3 ) was reported in early 2013.…”

mentioning

confidence: 99%

“…These features include viridicatumtoxin B’s EF spirosystem, its hindered quaternary carbon center at C15, its highly oxidized AB ring system, and the extensive substitution situated on the ABCD tetracyclic core of the molecule. Based on biosynthetic considerations [10] and the known structure of viridicatumtoxin A ( 1 ), [6] we tentatively assigned the relative configuration of viridicatumtoxin B ( 2 ) as shown in Figure 2. Our highly convergent strategy toward 2 was derived from the retrosynthetic analysis shown in Figure 2.…”

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confidence: 99%

Total Synthesis and Structural Revision of Viridicatumtoxin B

et al. 2013

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“…The cause may have been inaccurate scaling due to the large fraction of unobserved reflections but it was possible to solve the phase problem by selection of planes occurring most frequently in negative quartets (Silverton, Kabuto & Akiyama, 1978) and use of nine of these as magicinteger variables in the multisolution technique. The reliability of the solutions was assessed both by a weighted figure of merit and the NQEST test (DeTitta, Edmonds, Langs & Hauptman, 1975).…”

Section: 030(1)mentioning

confidence: 99%

Structure of 3-O-demethylcolchicine acetone solvate, C21H23NO6.C3H6O

Sharma¹,

Brossi²,

Silverton³

1985

Acta Crystallogr C

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Abstract. Mr=443.5 , orthorhombic, P2~2~21, a= 8.030(1), b=9.700(1), c=30.710(3) A, V= 2392.0 ,/k 3, Z --4, D m = 1.22 (1), D x = 1.231 g cm -3, 2(Cu Kct) = 1.5418/~, g = 7.58 cm -1, F(000) = 944, T= 293 K, wR =0.052 for 2788 reflections. This biologically relatively active colchinoid compound crystallizes as an acetone solvate. The intensity data were not of very high quality and the structure was refined first with data processed by standard methods and then with Bayesian techniques which produced an improvement in the precision of the results. The molecular conformation bears considerable resemblance to those of previously reported active colchinoids.

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The structure of chaetoglobosin A: a novel use of quartet invariants

Cited by 22 publications

References 9 publications

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

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

Total Synthesis and Structural Revision of Viridicatumtoxin B

Structure of 3-O-demethylcolchicine acetone solvate, C21H23NO6.C3H6O

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