4-O-TfO-2,3-anhydro-β-L-ribopyranosides as chiron: A formal synthesis of canadensolide

Al‐Abed, Yousef; Naz, Noshena; Mootoo, David R.; Voelter, Wolfgang

doi:10.1016/s0040-4039(96)02026-6

Cited by 20 publications

(2 citation statements)

References 12 publications

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“…An interesting natural product target is (−)-canadensolide, which was isolated from Penicillium canadense by McCorkindale and co-workers and exhibits antigerminative activity against fungi − and syntheses from enantioenriched natural sources − have been reported. With the exception of Honda's kinetic resolution (KR), , no syntheses based on asymmetric catalysis have appeared.…”

Section: Resultsmentioning

confidence: 99%

Addition/Oxidative Rearrangement of 3-Furfurals and 3-Furyl Imines: New Approaches to Substituted Furans and Pyrroles

2008

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Furans and pyrroles are important synthons in chemical synthesis and are commonly found in natural products, pharmaceutical agents, and materials. Introduced herein are three methods to prepare 2-substituted 3-furfurals starting from 3-furfural, 3-bromofuran, and 3-vinylfurans. Addition of a variety of organolithium, Grignard, and organozinc reagents (M-R) to 3-furfural provides 3-furyl alcohols in high yields. Treatment of these intermediates with NBS initiates a novel oxidative rearrangement that results in the installation of the R group in the 2 position of the 2-substituted 3-furfurals. Likewise, metalation of 3-bromofuran with n-BuLi and addition to benzaldehyde provides a furyl alcohol that is converted to 2-phenyl 3-furfural upon oxidative rearrangement. Enantioenriched disubstituted furans can be prepared starting with the Sharpless asymmetric dihydroxylation of 3-vinylfurans. The resulting enantioenriched diols undergo the oxidative rearrangement to furnish enantioenriched 2-substituted 3-furfurals with excellent transfer of asymmetry. This later method has been applied to the enantioselective preparation of an intermediate in Honda's synthesis of the natural product (-)-canadensolide. Mechanistic studies involving deuterium-labeled furyl alcohol suggest that the oxidative rearrangement proceeds through an unsaturated 1,4-dialdehyde intermediate. The alcohol then cyclizes onto an aldehyde, resulting in the elimination of water and rearomatization. On the basis of this proposed mechanism, we found that 3-furyl imines undergo the addition of organometallic reagents to provide furyl sulfonamides. Under the oxidative rearrangement conditions, 2-substituted 3-formyl pyrroles are formed, providing a novel route to these heterocycles. In contrast to the metalation of heterocycles, which often lead to mixtures of regioisomeric products, these new oxidative rearrangements of furyl alcohols and furyl sulfonamides generate only one regioisomer in each case.

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Section: Resultsmentioning

confidence: 99%

Addition/Oxidative Rearrangement of 3-Furfurals and 3-Furyl Imines: New Approaches to Substituted Furans and Pyrroles

2008

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“…1,2 Suitable intermediates and building blocks should bear appropriate functional groups for further transformations and in this respect, the oxirane is an ideal functional residue for subsequent regio-and stereoselective manipulations. 3 Amongst others, conversions of the oxirane to trithiocarbonates, thiazolidenes, thiazolines, deoxy sugars, deoxy azido sugars and glycopeptides have been carried out successfully.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 3,4-disaccharides from pyranosides and furanosides monomers, a novel class of potential bioactive disaccharides

Abbas¹,

Westermann²,

Voelter³

2007

Arkivoc

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ChemInform Abstract: 4‐O‐Tf‐2,3‐Anhydro‐β‐L‐ribopyranosides as Chiron: A Formal Synthesis of Canadensolide.

et al. 1997

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4-O-TfO-2,3-anhydro-β-L-ribopyranosides as chiron: A formal synthesis of canadensolide

Cited by 20 publications

References 12 publications

Addition/Oxidative Rearrangement of 3-Furfurals and 3-Furyl Imines: New Approaches to Substituted Furans and Pyrroles

Addition/Oxidative Rearrangement of 3-Furfurals and 3-Furyl Imines: New Approaches to Substituted Furans and Pyrroles

Synthesis of 3,4-disaccharides from pyranosides and furanosides monomers, a novel class of potential bioactive disaccharides

ChemInform Abstract: 4‐O‐Tf‐2,3‐Anhydro‐β‐L‐ribopyranosides as Chiron: A Formal Synthesis of Canadensolide.

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