3-Acyltetramic acid antibiotics. 3. An approach to the synthesis of Bu-2313

Ireland, Robert E.; Wardle, Robert B.

doi:10.1021/jo00385a024

Cited by 25 publications

(10 citation statements)

References 1 publication

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“…Swern oxidation or Dess-Martin 12 oxidation provided mainly the product of elimination. Our efforts to circumvent this problem by applying the combination of Swern oxidationWittig condensation procedure reported by Ireland and coworkers 13 for highly unstable aldehyde was likewise unsuccessful. Ultimately, the use of tetrapropylammonium perruthenate (TPAP), introduced by Ley 14 for the oxidation of alcohols proved successful.…”

Section: Methodsmentioning

confidence: 99%

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First Construction of a Saricandin Analog Corresponding to Papulacandin D

Hamdouchi¹,

Sanchez-Martinez²

2001

Synthesis

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The first total synthesis of a saricandin analog corresponding to papulacandin D has been achieved via a highly convergent synthetic strategy. A readily accessible chiral building block 3 was designed and prepared in large scale via an enantioselective reduction with pinanyl-9-BBN. The adaptability of compound 3 toward structural modifications and the highly convergent nature of the approach is illustrated in the construction of the side chain present in saricandin by Pd-catalyzed cross-coupling of 2 and 3 and sequences that include triple bond reduction of fragment C(5-16) and generation of the double bond (C4-C5) using Horner-Emmons reaction. The assembly of the spirocyclic monoglycoside with saricandin side chain is described. A practical technique for isolating the final product 1 after deprotection with TBAF is discussed. Compound 1 was evaluated for its antifungal activity in enzyme assay and cell based assays. However, in contrast the activity reported by Traxler for papulacandin D, the presence of the galactose moiety together with the short fatty acid in natural saricandin seem to be essential for the antifungal activity.In 1977, Traxler and coworkers reported the isolation and characterization of a family of antifungal antibiotics named papulacandins A, B, C and D from Papularia sphaerospema. 1 The compounds displayed potent in vitro activity against Candida albicans and various other yeasts and have been shown to inhibit b-1,3-glucan synthase, an enzyme involved in fungal cell wall biosynthesis. However, little or no efficacy has been found in animal models. The papulacandins A, B and C contain a spirocyclic diglycoside and two unsaturated fatty acids, linked as esters to two hydroxyl groups of the diglycosides. Papulacandin D, a monosaccharide relative is the simplest member of the family. The antifungal properties of papulacandin D juxtaposed with lack of access to natural material and the synthetically challenging structural feature make this compound interesting synthetic target. 2 The first total synthesis and full stereochemical assignment of papulacandin D was reported by Barrett and coworkers 3 in 1996. Although there is no evidence for a biosynthetic pathway it is possible that papulacandin D, lacking the galactose residue and the short fatty acid chain (Figure 1), is formed as intermediate in the biosynthesis of papulacandins A, B and C.Recently, a new potent antifungal antibiotic produced by the fungal culture, AB 2202W-161, named saricandin was isolated and characterized. 4 Guided by the hypothesis that saricandin may be formed following an analogous biosynthetic pathway to the papulacandins, we postulated that compound 1 (Figure) may be an intermediate in the process. 5 Herein we wish to describe the first total synthesis of compound 1. By analogy with the relationship between papulacandin D and A, compound 1 would address the question of how the biological profile of saricandin is affected by the absence of the galactose moiety together with the short fatty acid. Furthermore, the signifi...

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Section: Methodsmentioning

confidence: 99%

“…1 H and 13 C spectra were recorded on a 200 MHz Bruker AC-200P or a 300 MHz Bruker AMX, with CD 3 OD or CDCl 3 as solvents (without internal reference). 1 H NMR data were assigned by irradiation experiments 13. C NMR data were assigned by DEPT experiments.…”

mentioning

confidence: 99%

First Construction of a Saricandin Analog Corresponding to Papulacandin D

Hamdouchi¹,

Sanchez-Martinez²

2001

Synthesis

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“…All spectral data compare favourably with the literature. 19 (S)-3-(tert-Butyldimethylsilyloxy)butanal 4d. Using the general DIBALH reduction procedure described in general remarks, DIBALH solution (1.5 M in toluene, 4.0 mL, 6.0 mmol) was added to a stirred cold (−78 °C) solution of the above ester (1.23 g, 5.0 mmol) in dry toluene (15 mL).…”

Section: Methyl (R)-3-[(tert-butyldimethylsilyloxy)-2-methyl]propionatementioning

confidence: 99%

Enantioselective synthesis of the dioxabicyclo[3.2.1]octane core of the zaragozic acids via intramolecular Wacker-type cyclisation reactions

2004

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“…The synthesis of aldehyde 18 was achieved from commercially available b-hydroxy ester 15 which was first protected as TBS ether 16 applying standard conditions (Scheme 4). 25 The reduction of the ester moiety using lithium borohydride in THF afforded the corresponding primary alcohol 17 in good yield. 26 Oxidation was carried out under Parikh-Doering conditions which led to the formation of required aldehyde 18 in 86% yield.…”

Section: Introductionmentioning

confidence: 99%

Novel strategies for the synthesis of anthrapyran antibiotics: discovery of a new antitumor agent and total synthesis of (S)-espicufolin

et al. 2007

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Two high-yielding strategies for the synthesis of 4H-anthra[1,2-b]pyran antibiotics have been developed giving access to novel antitumor agent (ED(50) 1.5 microm) and to (S)-espicufolin (3). A key step for the assembly of the tetracyclic 4H-anthra[1,2-b]pyran-4,7,12-trione skeleton is the nucleophilic addition of an aryl lithium species onto an aldehyde which allows the introduction of either an ynone or 1,3-diketo side chain, serving as precursors for an acid-catalysed cyclisation.

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3-Acyltetramic acid antibiotics. 3. An approach to the synthesis of Bu-2313

Cited by 25 publications

References 1 publication

First Construction of a Saricandin Analog Corresponding to Papulacandin D

First Construction of a Saricandin Analog Corresponding to Papulacandin D

Enantioselective synthesis of the dioxabicyclo[3.2.1]octane core of the zaragozic acids via intramolecular Wacker-type cyclisation reactions

Novel strategies for the synthesis of anthrapyran antibiotics: discovery of a new antitumor agent and total synthesis of (S)-espicufolin

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