Conversion of Glucuronic Acid Glycosides to Novel Bicyclic <i>β</i>-Lactams

Durham, Timothy B.; Miller, Marvin J.

doi:10.1021/ol017026v

Cited by 31 publications

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References 29 publications

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“…These methods overwhelmingly make use of activated forms of carboxylic acids that are reacted with O -Bn hydroxylamine to give O -Bn hydroxamates, a conveniently protected form of free hydroxamic acids, each method differing in the activating group used. Hydrolysis is thus a prerequisite if very common precursors such as esters are to be converted into hydroxamates . Besides, many carboxylic acids proved reluctant in the activation step resulting in poor yields in the coupling reaction.…”

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One-Step Synthesis of O-Benzyl Hydroxamates from Unactivated Aliphatic and Aromatic Esters

2005

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We have developed a simple and high yielding one-step method for the synthesis of hydroxamate derivatives directly from a broad range of unactivated esters and the anion of O-benzyl-hydroxylamine generated in situ. The reaction takes place in minutes at -78 degrees C. Very importantly, the method was successfully employed with enolizable esters, including chiral alpha-amino acid esters and peptides, with no trace of racemization/epimerization at the alpha carbon detected.

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One-Step Synthesis of O-Benzyl Hydroxamates from Unactivated Aliphatic and Aromatic Esters

2005

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“…The donors 6 and 7 were also prepared, via glycal 4 , because of their potential for the synthesis of 2‐deoxyglycosides, which are of biological interest 7. Thus, the reaction of the allyl ester 3 with hydrogen bromide in acetic acid gave a glycosyl bromide intermediate and this was subsequently converted into 4 by treatment with zinc dust, copper( II ) sulfate, and sodium acetate in aqueous acetic acid as described previously for the corresponding methyl ester 8. The allyl protecting group could be removed from 4 , to leave the glycal intact, by using [Pd(PPh 3 ) 4 ] and pyrrolidine in acetonitrile to give 5 9.…”

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confidence: 99%

Glycosidation Reactions of Silyl Ethers with Conformationally Inverted Donors Derived from Glucuronic Acid: Stereoselective Synthesis of Glycosides and 2‐Deoxyglycosides

et al. 2004

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Stereoselective glycoside synthesis is of interest because of the biological and medical relevance of oligosaccharides, glycoproteins, glycolipids, [1] and other carbohydrate derivatives, [2] and a range of strategies have been developed to produce these compounds.[3] The 1,6-lactone derivative 2 (see Scheme 1) has potential for use in the synthesis of 1,2-cisglycosides [4] but its application has been limited because of the low yields obtained from its reaction with alcohols.[5] We now report that the SnCl 4 -catalyzed coupling of silyl ethers [6] with 2 provides a-O-glucuronides in significantly improved yields without loss of stereoselectivity. The methodology has been extended to the related 2-deoxylactones, which give aor b-glycosides depending on the structure of the donor.The preparation of 2 was carried out via the mixed anhydride 1 (Scheme 1) by an improved and shorter procedure than that previously described.[5] The donors 6 and 7 were also prepared, via glycal 4, because of their potential for the synthesis of 2-deoxyglycosides, which are of biological interest.[7] Thus, the reaction of the allyl ester 3 with hydrogen bromide in acetic acid gave a glycosyl bromide intermediate

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Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

Ferrier

Zubkov

2003

Organic Reactions

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Various elimination procedures conducted on appropriate pyranoid and furanoid carbohydrate derivatives, especially on O ‐protected glycosyl halides afford cyclic vinyl ethers which Fischer (inappropriately) named glycals. These are used extensively in general organic synthesis and for the preparation of non‐carbohydrate natural products as well as biologically important complex carbohydrates and glycoconjugates. The best known member, tri‐ O ‐acetyl‐D‐glucal, is normally made from tetra‐ O ‐acetyl‐alpha‐D‐glucopyranosyl bromide, is commercially available, and is used very frequently in this chapter to represent the family in examples of the reactions under discussion. Because of the pronounced region‐ and stereoselectivities with which their addition reactions can be conducted, glycal derivatives are of major importance in synthesis. They also, however, take part in rearrangement processes that, likewise, have proved useful for synthesis. The principal one involves nucleophilic substitution of the allylic group with allylic rearrangement and results in products having double bonds in the 2, 3 positions and new substituents at the anomeric centers. By far the simplest and most commonly used way to this conversion involves the removal of the allylic substituent of the glycal and the generation of highly resonance‐stabilized oxocarbenium ion intermediate. This may then react with nucleophiles at the anomeric center to give products as mixtures of diastereomers. Many examples and variations of this theme are described and form the major part of this chapter, but other ways are also considered Almost no formal mechanistic studies have been carried out on the reactions in this chapter. Categorization of mechanism required for the treatment of this topic has been done on the basis of conditions used, product identification and largely, chemical intuition.

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Conversion of Glucuronic Acid Glycosides to Novel Bicyclic β-Lactams

Cited by 31 publications

References 29 publications

One-Step Synthesis of O-Benzyl Hydroxamates from Unactivated Aliphatic and Aromatic Esters

One-Step Synthesis of O-Benzyl Hydroxamates from Unactivated Aliphatic and Aromatic Esters

Glycosidation Reactions of Silyl Ethers with Conformationally Inverted Donors Derived from Glucuronic Acid: Stereoselective Synthesis of Glycosides and 2‐Deoxyglycosides

Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

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