- Asymmetric synthesis of acetomycin
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The synthesis of (-)-acetomycin 1, a highly functionalized γ-lactone with antitumor activity, was achieved in five steps with nearly complete enantioselectivity. The key step was realized by a large scale lipase R catalyzed esterification of 5-hydroxy-4-methyl-2(5H)-furanone 2 providing (- )-(5R)-5-acetoxy-4-methyl-2(5H)-furanone 3 with an e.e. of 99%.
- Kinderman, Sape S.,Feringa, Ben L.
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- Construction of Consecutive Chiral Non-Racemic Quaternary and Tertiary Carbon Centers: A Short Synthetic Route to (-)-Acetomycin
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Regio- and diastereoselective nucleophilic substitution of 2-methylacetoacetate with a chiral non-racemic π-allyl Pd complex creates consecutive chiral non-racemic quaternary and tertiary carbon centers. σ-Bond formation between the reface of the π-allyl Pd complex and the re-face of the enol acetoacetate was controlled by the o-(diphenylphosphanyl)-arylcarboxylic acid ligand selectively. (-)-Acetomycin was synthesized in seven steps using this key approach. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Uenishi, Jun'ichi,Kawatsura, Motoi,Ikeda, Daiji,Muraoka, Nobuhiro
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p. 3909 - 3912
(2007/10/03)
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- Total synthesis of (+/-)-acetomycin and design of esterase-resistant analogs.
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The synthesis of acetomycin and related analogs was investigated. Acetomycin was synthesized from diethyl allyl(methyl)malonate in 6.5% yield over 18 steps. The total number of steps was improved compared to our previous synthesis; i.e., four steps shorte
- Uenishi,Kobayashi,Komine,Okadai,Yonemitsu,Sasaki,Yamada
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p. 517 - 523
(2007/10/03)
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- Unexpected Contrasteric Alkylation Leading to a Model for Five-Membered Ring Enolate Alkylation: Short Stereoselective Synthesis of (+/-)-Acetomycin
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It is well established that the alkylation of cyclic enolates 1 bearing an asymmetric center at the β-position should provide mainly lactones 2 where the electrophile (E(+)) ends up trans to the β-substituent (R2).Our interest in such processes lies in the fact that according to this principle, alkylation of 1a with methyl iodide should provide direct access to (+/-)-acetomycin (2a).However, this reaction unexpectedly afforded the contrasteric alkylation product 3a ((+/-)-3-epi-acetomycin) with high diastereoselectivity.To elucidate this observation, alkylation studies have been carried out on various enolates 1.As normally expected, when R2 and R3 are alkyl groups, only product 2 is obtained.On the other hand, when R3 is an acetoxy group or an alkoxy group and methyl iodide is used as electrophile, the contrasteric products 3 are predominant.With sterically more demanding electrophiles, the "normal" alkylation products 2 are obtained in moderate to extremely high selectivity.Thus, the use of 1,3-dithienium tetrafluoroborate, a bulky methyl equivalent, allowed us to complete a stereoselective syntheses of (+/-)-acetomycin.These results led to the elaboration of a model for five-membered ring enolate alkylation based on steric and stereoelectronic effects, as well as ring conformations.
- Sprules, Tara J.,Lavallee, Jean-Francois
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p. 5041 - 5047
(2007/10/02)
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- A Selective Baeyer-Villiger Oxidation: A Total Synthesis of (-)-Acetomycin
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A short, stereoselective synthesis of (-)-acetomycin (2) from L-threonine is reported.The final step in the synthesis is a selective Baeyer-Villiger oxidation that discriminates between two methyl ketones.
- Ziegler, Frederick E.,Kim, Hakwon
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p. 7669 - 7672
(2007/10/02)
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- Stereoselective synthesis of (±)-4-epi-acetomycin by the ester enolate carroll rearrangement
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The synthesis of (+-)-4-epi-acetomycin has been completed by the steroselective ester enolate (Carroll rearrangement of (E)-2-butenyl 2-methylacetoacetate, followed by ozonolysis and acetylation. The synthesis of (+)- acetomycin and its three diastereomers by a related route is also described.
- Echavarren, Antonio M.,De Mendoz, Javier,Prados, Pilar,Zapata, Amparo
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p. 6421 - 6424
(2007/10/02)
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- TOTAL SYNTHESIS OF (+/-)-ACETOMYCIN
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A stereocontrolled total synthesis of (+/-)-Acetomycin (1) is described.The acyloxy group was successfully introduced from sterically hindered α-side onto the γ-butyrolactone ring.
- Uenishi, Jun'ichi,Okadai, Takeshi,Wakabayashi, Shoji
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p. 3381 - 3384
(2007/10/02)
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- Total synthesis of (-)-acetomycin
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Enantiospecific total synthesis of the rifled antibiotic (1) has been completed. The pentasubstituted tetrahydrofuran (3), efficiently obtained from D-glucose, was used as an enantiomerically pure starting material.
- Tadano, Kin-Ichi,Ishihara, Jun,Ogawa, Seiichiro
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p. 2609 - 2612
(2007/10/02)
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