Studies on Pentenomycins. II. The Structures of Pentenomycin I and II, New Antibiotics

Umino, Kimio; Takeda, Nobuhiro; Ito, Yukio; Okuda, Tomoharu

doi:10.1248/cpb.22.1233

Cited by 46 publications

(18 citation statements)

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“…[48] To the best of our knowledge, five asymmetric syntheses of this compound have been reported to date, [49] with four of them requiring carbohydrates as starting materials; this implies the use of long and lineal synthetic sequences (10-20 chemical steps). A very efficient enantioselective four-step synthesis of (À)-pentenomycin I from the vinyl sulfoxide (R)-1 i, taking advantage of the convergent formation of the cyclopentenone ring by a PK reaction, is shown in Scheme 16.…”

Section: Resultsmentioning

confidence: 99%

“…M.p. (À)-Pentenomycin I (19): [48] A solution of cyclopentenone 18 (64 mg, 0.10 mmol) in 2 m HCl (4 mL) was stirred at RT for 6 h. The mixture was washed with CH 2 Cl 2 (3 5 mL) and the aqueous layer was concentrated. The residue was purified by chromatography (ethyl acetate/methanol 10:1) to afford (À)-(2S,3S)-pentenomycin (11 mg, 76 %, colorless oil).…”

Section: -N-mentioning

confidence: 99%

“…[a] D = À32 (c = 0.2, EtOH) (natural product: [48] [a] (À)-Pentenomycin I triacetate: [55] Acetic anhydride (101 mL, 1.07 mmol) was added to a solution of pentenomycin (11 mg, 0.08 mmol) in ice-cold pyridine (204 mL, 2.52 mmol) under an argon atmosphere. After 24 h at RT, water (5 mL) was added and the mixture was extracted with ethyl acetate (3 5 mL).…”

Section: -N-mentioning

confidence: 99%

See 2 more Smart Citations

Vinyl Sulfoxides as Stereochemical Controllers in Intermolecular Pauson–Khand Reactions: Applications to the Enantioselective Synthesis of Natural Cyclopentanoids

Rivero

Alonso

Carretero

2004

Chemistry A European J

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The use of sulfoxides as chiral auxiliaries in asymmetric intermolecular Pauson-Khand reactions is described. After screening a wide variety of substituents on the sulfur atom in alpha,beta-unsaturated sulfoxides, the readily available o-(N,N-dimethylamino)phenyl vinyl sulfoxide (1 i) has proved to be highly reactive with substituted terminal alkynes under N-oxide-promoted conditions (CH3CN, 0 degrees C). In addition, these Pauson-Khand reactions occurred with complete regioselectivity and very high diastereoselectivity (de=86->96 %, (S,R(S)) diastereomer). Experimental studies suggest that the high reactivity exhibited by the vinyl sulfoxide 1 i relies on the ability of the amine group to act as a soft ligand on the alkyne dicobalt complex prior to the generation of the cobaltacycle intermediate. On the other hand, both theoretical and experimental studies show that the high stereoselectivity of the process is due to the easy thermodynamic epimerization at the C5 center in the resulting 5-sulfinyl-2-cyclopentenone adducts. When it is taken into account that the known asymmetric intermolecular Pauson-Khand reactions are limited to the use of highly reactive bicyclic alkenes, mainly norbornene and norbornadiene, this novel procedure constitutes the first asymmetric version with unstrained acyclic alkenes. As a demonstration of the synthetic interest of this sulfoxide-based methodology in the enantioselective preparation of stereochemically complex cyclopentanoids, we have developed very short and efficient syntheses of the antibiotic (-)-pentenomycin I and the (-)-aminocyclopentitol moiety of a hopane triterpenoid.

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Section: Resultsmentioning

confidence: 99%

Section: -N-mentioning

confidence: 99%

Section: -N-mentioning

confidence: 99%

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Vinyl Sulfoxides as Stereochemical Controllers in Intermolecular Pauson–Khand Reactions: Applications to the Enantioselective Synthesis of Natural Cyclopentanoids

Rivero

Alonso

Carretero

2004

Chemistry A European J

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“…57 Of the five asymmetric syntheses of this compound reported to date 58 four involve the use of carbohydrates as starting materials, which imply the use of long synthetic sequences. A very efficient enantioselective four-step synthesis of (-)-pentenomycin I from the vinyl sulfoxide (R)-37i is shown in Scheme 22.…”

Section: Applications To the Enantioselective Synthesis Of Natural Cymentioning

confidence: 99%

Pauson-Khand Reactions of Alkenyl Sulfones and Alkenyl Sulfoxides: Applications in Asymmetric Synthesis

Rivero¹,

Adrio²,

Carretero³

2004

Synlett

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Unlike other types of electron-deficient alkenes, alkenyl sulfones and alkenyl sulfoxides are excellent alkene partners in Pauson-Khand reactions (PKR). In the case of the intramolecular PKR of appropriately substituted 1-sulfinyl-1,6-enynes and 1-sulfonyl-3-oxygenated-1,6-enynes novel stereoselective processes and applications in asymmetric synthesis have been developed. Furthermore, using the cobalt-chelating dimethylaminophenyl vinyl sulfoxide as substrate, their intermolecular PKR with terminal alkynes provide the first intermolecular asymmetric version of PKR with nonstrained alkenes. The resulting 5-sulfinyl-2-cyclopentenones are versatile intermediates in the enantioselective synthesis of natural cyclopentanoids.

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“…spectrum that was identical to that reported for natural pentenomycin I (Refs. 34,35). By combining the latter two steps without intermediate purification of 22.…”

Section: Bzo~~~ ---->~ ~9mentioning

confidence: 99%

Chiral syntheses of the antibiotics anisomycin and pentenomycin from carbohydrates

Verheyden¹,

Richardson²,

Bhatt³

et al. 1978

Pure and Applied Chemistry

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-Syntheses of the natural, optically active forms of the antibiotics anisomycin and pentenomycin are described using simple glucose derivatives as chiral starting materials. The key step in the synthesis of anisomycin is the formation of a pyrrolidine ring embodying all three of the desired asymmetric centers via intramolecular nucleophilic displacement of a 3-Q-tosyl function in an-;ppropriately substituted 6-amino-6-deoxy-ß-~-talofuranose derivative. Further elaboration involves the liberation of an aldehyde group by periodate oxidation of the 1,2-diol, Grignard coupling and removal of extraneous functions and blocking groups by several reductive steps.The syntheses of pentenomycin, and its simpler analog 6-deoxypentenomycin, proceed via conversion of 3-benzyloxymethyl and 3-methyl derivatives of 1,2:5,6-di-Q-isopropylidene-a-Q-allofuranose, respectively, into the respective 3-substituted methyT 2,3-cycloalkylidene-5-deoxy-Q-erythro-pent-4-enofuranosides. Acidic hydrolysis of the latter gives the-related 4-ketoaldehydes that undergo intramolecular aldol condensations to form the appropriately substituted 2-cyclopenten-1-ones that can be converted into the target compounds.It is axiomatic in organic chemistry that the synthesis of an optically active product must make use of chiral substances, either as resolving agents or as synthetic intermediates. From the point of view of overall efficiency, the use of an appropriate chiral starting material is of particular attraction. This approach has found extensive use over the years, and syntheses of a great variety of optically active natural products have been described starting from readily available chiral substances such as amino acids and simple terpenes (Ref. 1). In spite of the fact that carbohydrates constitute one of Nature's richest sources of chirality, only in recent years have these substances found wide use as starting materials for asymmetric syntheses. This stems, to a considerable degree, from a lang standing aversion an the part of many organic chemists to work with carbohydrates, which were considered to be mainly intractable syrups. With the advent of improved and more selective protecting groups and, in particular, the extensive application of contemporary instrumental analysis, carbohydrate chemistry is now enjoying a new image. As synthetic intermediates, carbohydrates are now becoming recognized as readily available, polyfunctional molecules containing several sites of predictably controllable asymmetry. In recent years this has led to the use of carbohydrate derivatives as intermediates in the synthesis of a nurober of optically active natural products of widely divergent structures. Hanessian and Raucourt (Ref. 6). In the present paper we further extend this general approach through a description of the syntheses of two optically active antibiotics, anisomycin (1) and pentenomycin (2), starting from ~-glucose.--Anisomycin (1) was isolated from two strains of Streptomyces by Sobin and Tanner of Chas. (Refs. l7, 18) have also prepa...

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Studies on Pentenomycins. II. The Structures of Pentenomycin I and II, New Antibiotics

Cited by 46 publications

References 0 publications

Vinyl Sulfoxides as Stereochemical Controllers in Intermolecular Pauson–Khand Reactions: Applications to the Enantioselective Synthesis of Natural Cyclopentanoids

Vinyl Sulfoxides as Stereochemical Controllers in Intermolecular Pauson–Khand Reactions: Applications to the Enantioselective Synthesis of Natural Cyclopentanoids

Pauson-Khand Reactions of Alkenyl Sulfones and Alkenyl Sulfoxides: Applications in Asymmetric Synthesis

Chiral syntheses of the antibiotics anisomycin and pentenomycin from carbohydrates

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