A Flexible Synthesis of Azasugars and Homoazasugars via Olefin Metathesis

Huwe, Christoph M.; Blechert, Siegfried

doi:10.1055/s-1997-1497

Cited by 67 publications

(23 citation statements)

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“…Albeit an analogous ring-closing cross-metathesis reaction [19] of the precursor (R)-15 without a tert-butyldimethylsilyl group using Grubbs I catalyst [20a] has been described to give the corresponding 3,4-dehydroprolinol derivative in 95 % yield, [21] the same ring closure of (R)-15 turned out to be more difficult. With the Grubbs I catalyst, an incomplete conversion occurred, and this could not be improved significantly employing the Grubbs II [20b] or the Hoveyda-Grubbs catalyst.…”

Section: Resultsmentioning

confidence: 99%

An Improved Synthesis of 3,4‐(Aminomethano)proline and Its Incorporation into Small Oligopeptides

et al. 2006

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Starting from the readily available Garner aldehyde, a new synthesis of diastereomerically and enantiomerically pure 3,4‐(aminomethano)prolinol (2R,1′S,3S,4S)‐17 has been developed using simple and easily scalable transformations. The protected diamino alcohol (2R,1′S,3S,4S)‐17 has been shown to be an appropriate compound for the exchange of protecting groups. Final Jones oxidation furnished the correspondingly protected diamino acids in high yields. The newly synthesized Fmoc/Boc‐protected 3,4‐(aminomethano)proline (Amp) derivatives, which are proline mimics as well as bicyclic γ‐amino acids, depending on the orthogonal protecting group pattern, were employed for solid‐phase peptide synthesis with the Fmoc strategy. Thus, the features of Amp as a γ‐amino acid residue (γ‐Amp) were investigated in the preparation of alternating α/γ‐amino acid sequences. The obtained highly homogeneous products were characterized by circular dichroism spectroscopy. The fact that the dichroic properties of the α/γ‐oligopeptides were independent from the solvent used (water or methanol) suggests the presence of a preferred conformation. These results are encouraging for the development of foldamers based on γ‐Amp units. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Resultsmentioning

confidence: 99%

An Improved Synthesis of 3,4‐(Aminomethano)proline and Its Incorporation into Small Oligopeptides

et al. 2006

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“…This principle was first realized by Blechert et al: enantiomerically pure triene 11 can be cyclized selectively to either diastereomer 12 or 13, depending on the choice of the catalyst [56]. The authors also demonstrated that the exoand endocyclic C-C-double bonds in 13 can be selectively manipulated by careful ozonolysis and dihydroxylation, which opens up a pathway to the stereoselective de novo synthesis of azasugar 15 (Scheme 6) [57]. Scheme 4.…”

Section: Trienes With C1-symmetry (Diastereoselective Rcm)mentioning

confidence: 99%

“…Scheme 6. Differentiation of diastereotopic groups for azacycle synthesis [56,57]. Hirama et al investigated a very elegant approach to the AB-ring fragment of ciguatoxin (18) using a diastereoselective ring closing metathesis of 16, followed by cross metathesis with enantiomerically pure diacetoxybutene [58].…”

Section: Trienes With C1-symmetry (Diastereoselective Rcm)mentioning

confidence: 99%

"Ring Closing Metathesis of Substrates Containing more than two C-Cdouble Bonds: Rapid Access to Functionalized Heterocycles"

Schmidt¹,

Hermanns

2006

COC

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In most cases where ring closing metathesis is applied to the synthesis of heterocycles, α,ω-dienes are used as precursors. If substrates containing more than two double bonds are subjected to a metathesis reaction, carba-or heterocycles bearing additional exocyclic alkene functionality result, or multiple ring closing processes occur. This offers interesting and potentially very useful synthetic perspectives. On the other hand, selectivity problems need to be addressed as the cyclization of substrates with more than two double bonds available for olefin metathesis may result in constitutional isomers or stereoisomers. This review highlights problems and opportunities evolving from ring closing metathesis of tri-, tetra-, and polyenes as a strategy for the selective synthesis of functionalized heterocycles. The chapter on RCM of trienes is subdivided according to the symmetry of the metathesis precursor. The following two chapters deal with the double or multiple RCM of tetra-or polyenes. These processes are further classified according to the preferred cyclization mode. Finally, the application of cascade or domino metathesis reactions to the synthesis of heterocycles will be discussed. These processes can be classified into those where exclusively C-C-double bonds take part in the metathesis reaction, and those where one or more C-C-triple bonds are involved.

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“…Owing to its interesting enzyme-inhibitory activity and its potential as a synthon, 73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89, & 90 vinylglycine has attracted the attention of synthetic chemists. Hence, a variety of asymmetric synthetic methodologies to access D-and L-vinylglycine are available in the current literature.…”

Section: Asymmetric Synthesismentioning

confidence: 99%

α‐Vinylic Amino Acids: Occurrence, Asymmetric Synthesis, and Biochemical Mechanisms

et al. 2006

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This report presents an overview of the family of naturally occurring "vinylic" amino acids, namely those that feature a CC double bond directly attached to the α-carbon, along the side chain. Strategies that have been brought to bear on the stereocontrolled synthesis of these olefi nic amino acids are surveyed. The mechanistic diversity by which such "vinylic triggers" can be actuated in a PLP (pyridoxal phosphate) enzyme active site is then highlighted by discussion of vinylglycine (VG), its substituted congeners, particularly AVG [4E-(2′-aminoethoxy)vinylglycine], and a naturally occurring VG-progenitor, SMM [(S)-methylmethionine].

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A Flexible Synthesis of Azasugars and Homoazasugars via Olefin Metathesis

Cited by 67 publications

References 0 publications

An Improved Synthesis of 3,4‐(Aminomethano)proline and Its Incorporation into Small Oligopeptides

An Improved Synthesis of 3,4‐(Aminomethano)proline and Its Incorporation into Small Oligopeptides

"Ring Closing Metathesis of Substrates Containing more than two C-Cdouble Bonds: Rapid Access to Functionalized Heterocycles"

α‐Vinylic Amino Acids: Occurrence, Asymmetric Synthesis, and Biochemical Mechanisms

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