Noniterative approach to the total asymmetric synthesis of 15-carbon polyketides and analogs with high stereodiversity

Vogel, Pierre; Gerber‐Lemaire, Sandrine; Carmona, Ana T.; Meilert, Kai Torsten; Schwenter, Marc‐Etienne

doi:10.1351/pac200577010131

Cited by 18 publications

(3 citation statements)

References 9 publications

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“…The previously reported diacetate meso-12 [10] was treated with Bu 3 SnH and AIBN (toluene, 80°C), followed by methanolysis under classical conditions, to provide meso-11 (66 % yield). Then, we submitted dialkene meso-11 to double oxidative cleavage.…”

Section: Resultsmentioning

confidence: 99%

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Asymmetric Synthesis of the Polyol Subunit of the Polyene Macrolide Antibiotic RK‐397

et al. 2006

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A total asymmetric synthesis of the polyol subunit of the polyene macrolide antibiotic RK‐397 has been developed by the stereoselective functionalization of (1R,1′S,6S,6′R)‐3,3′‐methylenebis(cyclohept‐3‐ene‐1,6‐diol). The pathway generates a large variety of stereoisomeric intermediates and thus can be applied to the preparation of analogues of this natural antibiotic. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Resultsmentioning

confidence: 99%

“…For that purpose, the previously reported exo-diacetate meso-18 [10] was treated with BCl 3 to afford the corresponding dichlorodiol intermediate, which was subsequently converted into the bis(p-methoxybenzoate) meso-19 in 87 % yield (two steps). Dechlorination with Bu 3 SnH and AIBN (toluene, 80°C) afforded meso-20 (75 % yield).…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis of the Polyol Subunit of the Polyene Macrolide Antibiotic RK‐397

et al. 2006

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“…Interestingly, double reduction of meso-8 using K-selectride or Merwein-Pondorf-Verley conditions led respectively to diacetate 33 and 34 with excellent ste-reocontrol (Scheme 7). [25] A SN 2 '-type-8oxa bridge cleavage induced by BCl 3 , followed by esterification of the intermediate dichlorodiol and radical reduction provided diolefin 35. [26] Desymmetrization was then achieved by means of the Sharpless asymmetric dihydroxylation to deliver the corresponding diol 36 with 98.4% enantiomeric excess.…”

Section: From 11'-methylenedi(3-oxo-8-oxabicyclo[321]oct-6-ene) Tomentioning

confidence: 99%

Preparation and Synthetic Applications of 8-Oxabicyclo[3.2.1]oct-6-en-3-one Derivatives

Favre¹,

Gerber‐Lemaire²,

Vogel³

2008

Chimia

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The development of efficient routes to multi-gram quantities of chiral synthons is a key issue in the total synthesis of natural products and analogues. The conformationally defined and rigid 8-oxabicyclo[3.2.1]oct-6-en-3-one template is an appealing starting material for the development of non-iterative approaches to polyoxygenated fragments that are found in a large variety of biologically relevant natural compounds. Desymmetrization and resolution procedures, stereoselective functionalizations and double-chain elongations represent attractive strategies for such synthetic challenges.adducts. Further stereoselective functionalization of the rigid bicyclic templates then provides an efficient access to stereodefined polyketides. We give here an overview of noniterative approaches to polyoxygenated compounds from 8-oxabicyclo[3.2.1]oct-6-en-3-one derivatives that are generated through [4+3] cycloaddition reactions. [4+3]-Cycloadditions of Oxyallyl Cations to Furan and DerivativesThe generation of the 8-oxabicyclo[3.2.1]oct-6-en-3-one template can be achieved by a [4+3] cycloaddition of furan to oxyallyl cations of type 3 (Scheme 1). These stabilized cations 3 can be produced from tetrahalogenoketones 1 in the presence of a reducing metal [1] or a tertiary amine in an ionizing solvent. [2] The resulting rigid bicyclic system is a synthon of choice for stereoselective transformations as illustrated by the reduction of ketone 4 , with L-selectride or SmI 2 which provides the endo-alcohol 5 and the exo -alcohol 6 , respectively. In the late 1990s Vo gel and co-workers extended this powerful strategy to a double [4+3] cycloaddition of 2,2-methylenebis(furan) 7 to oxyallyl cations which gives rise to a mixture of bisbicycloadducts meso-8 and threo-8 in a 45:55 ratio (60% yield). [3] Several other precursors of oxyallyl cations were inves-

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(4+3) Cycloadditions of Allylic and Related Cations

Harmata,

Tu,

Clark

2024

Organic Reactions

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The reaction of allylic cations with 1,3‐dienes is formally equivalent to the Diels–Alder reaction but leads to seven‐membered rings. An allylic cation contains 2 pi electrons, and is thus precisely analogous to an alkene and, like the latter, can function as a dienophile. The substituent at the central carbon of the allylic cation serves to terminate the reaction. Most often, this substituent is an oxyanion or a silyl ether, but other groups have been used. These (4+3) cycloadditions can proceed via mechanisms that range from stepwise to concerted. Diastereoselectivity, regioselectivity, and enantioselectivity have all been achieved, though there are still opportunities for the development of new reactions in this area. Asymmetric catalysis and enzymatic catalysis of such reactions is in its infancy. More recent advances center on cations that are related to benzylic cations but involve electron rich heterocycles such as furans, indoles, thiophenes and related structures. This chapter covers advances in (4+3) cycloadditions of allylic and related cations from 1997 to 2017, with supplemental references added to bring the work up to date through 2023. It illustrates both the growth in technical progress and theoretical understanding of this reaction during that time.

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Noniterative approach to the total asymmetric synthesis of 15-carbon polyketides and analogs with high stereodiversity

Cited by 18 publications

References 9 publications

Asymmetric Synthesis of the Polyol Subunit of the Polyene Macrolide Antibiotic RK‐397

Asymmetric Synthesis of the Polyol Subunit of the Polyene Macrolide Antibiotic RK‐397

Preparation and Synthetic Applications of 8-Oxabicyclo[3.2.1]oct-6-en-3-one Derivatives

(4+3) Cycloadditions of Allylic and Related Cations

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