Synthesis of Carbocyclic Hydantocidins via Regioselective and Diastereoselective Phosphine-Catalyzed [3 + 2]-Cycloadditions to 5-Methylenehydantoins

Pham, Tien; Pyne, Stephen G.; Skelton, Brian W.; White, Allan H.

doi:10.1021/jo050827h

Cited by 98 publications

(40 citation statements)

References 53 publications

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“…Most of the reported syntheses of hydantocidin and its analogues have revolved around the use of sugar derivatives to generate the desired stereochemistry of the hydroxyl groups in the furan ring. However, Pham and co-workers reported the preparation of carbocyclic hydantocidins 96 and 97 from ethyl 2-butynoate and N , N ′-diprotected-5-methylenehydantoins using as key step a phosphine-catalysed [3 + 2]-cycloaddition to generate the spiro-heterocyclic system ( Scheme 21 ) [ 63 ]. Thus, the cycloaddition reaction of the 5-methylenehydantoin 108 with the ylide that was generated in situ from the reaction of ethyl 2-butynoate 109 and tributylphosphine afforded ester 110 , which was then isomerized to ester 111 on treatment with potassium bistrimethylsilylamide.…”

Section: Synthesis Of Hydantoinsmentioning

confidence: 99%

Synthesis of Spironucleosides: Past and Future Perspectives

2017

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Spironucleosides are a type of conformationally restricted nucleoside analogs in which the anomeric carbon belongs simultaneously to the sugar moiety and to the base unit. This locks the nucleic base in a specific orientation around the N-glycosidic bond, imposing restrictions on the flexibility of the sugar moiety. Anomeric spiro-functionalized nucleosides have gained considerable importance with the discovery of hydantocidin, a natural spironucleoside isolated from fermentation broths of Streptomyces hygroscopicus which exhibits potent herbicidal activity. The biological activity of hydantocidin has prompted considerable synthetic interest in this nucleoside and also in a variety of analogues, since important pharmaceutical leads can be found among modified nucleoside analogues. We present here an overview of the most important advances in the synthesis of spironucleosides.

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Section: Synthesis Of Hydantoinsmentioning

confidence: 99%

Synthesis of Spironucleosides: Past and Future Perspectives

2017

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“…Instead of a tertiary amine, one can employ an enantiomerically pure chiral N-heterocyclic carbene as the nucleophilic catalyst (Scheme 66B) [414]. The allylic anions of type 161 (Scheme 63) resulting from the nucleophilic addition of triphenylphosphine to conjugated yne-esters, or allene carboxylic esters, can be reacted with activated alkenes to give products of (3+2)-annulation (Scheme 67) [415][416][417]. The (3+2)-cycloaddition of 172 gives ylide intermediates 173.…”

Section: Nucleophilic Catalysis Of Cycloadditionsmentioning

confidence: 99%

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

et al. 2016

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Catalysis fulfills the promise that high-yielding chemical transformations will require little energy and produce no toxic waste. This message is carried by the study of the evolution of molecular catalysis of some of the most important reactions in organic chemistry. After reviewing the conceptual underpinnings of catalysis, we discuss the applications of different catalysts according to the mechanism of the reactions that they catalyze, including acyl group transfers, nucleophilic additions and substitutions, and C-C bond forming reactions that employ umpolung by nucleophilic additions to C=O and C=C double bonds. We highlight the utility of a broad range of organocatalysts other than compounds based on proline, the cinchona alkaloids and binaphthyls, which have been abundantly reviewed elsewhere. The focus is on organocatalysts, although a few examples employing metal complexes and enzymes are also included due to their significance. Classical Brønsted acids have evolved into electrophilic hands, the fingers of which are hydrogen donors (like enzymes) or other electrophilic moieties. Classical Lewis base catalysts have evolved into tridimensional, chiral nucleophiles that are N-(e.g., tertiary amines), P-(e.g., tertiary phosphines) and C-nucleophiles (e.g., N-heterocyclic carbenes). Many efficient organocatalysts bear electrophilic and nucleophilic moieties that interact simultaneously or not with both the electrophilic and nucleophilic reactants. A detailed understanding of the reaction mechanisms permits the design of better catalysts. Their construction represents a molecular science in itself, suggesting that sooner or later chemists will not only imitate Nature but be able to catalyze a much wider range of reactions with high chemo-, regio-, stereo-and enantioselectivity. Man-made organocatalysts are much smaller, cheaper and more stable than enzymes.

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“…Using this methodology, Pyne prepared carbocyclic analogues of hydantocidin (Scheme 8). 12 In the cyclization step, under tributylphosphine catalysis, the desired α-regioisomer of the spirocyclic product was obtained in 81% yield. Another product was isolated in 6% yield, which resulted from a second cyclization reaction of the minor γ-adduct with the 2-butynoate.…”

Section: Account Syn Lettmentioning

confidence: 99%

Phosphine Organocatalysis for the Synthesis of Spirocyclic Compounds

Voituriez

Marinetti

Gicquel

2014

Synlett

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This account describes the use of phosphines as simple organocatalysts that catalyze the synthesis of complex spirocyclic compounds. Besides our own results, coverage of relevant literature in this field is also provided, including asymmetric variants and synthetic applications. Cycloaddition Reactions Using Ynone Derivatives 5 Cycloaddition Reactions Involving Methyl Vinyl Ketone Derivatives 6 Miscellaneous Reactions 7 Conclusions

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Synthesis of Carbocyclic Hydantocidins via Regioselective and Diastereoselective Phosphine-Catalyzed [3 + 2]-Cycloadditions to 5-Methylenehydantoins

Cited by 98 publications

References 53 publications

Synthesis of Spironucleosides: Past and Future Perspectives

Synthesis of Spironucleosides: Past and Future Perspectives

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

Phosphine Organocatalysis for the Synthesis of Spirocyclic Compounds

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