Stereoselective Indium-Promoted Allylation of γ-Hydroxy-γ-Lactones under Aqueous Conditions. The Neighboring Carboxyl Effect

Bernardelli, Patrick; Paquette, Leo A.

doi:10.1021/jo9716800

Cited by 32 publications

(31 citation statements)

References 9 publications

(6 reference statements)

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“…As would be expected from our interpretation discussed above, the effect due to the 4-methyl group dominates. [23] The reaction between 5-hydroxylactone 6 and allylsilane 8 may proceed via an open-chain β-formylcarboxylic acid, as discussed for related examples in the literature, [24] or via a highly electrophilic, cyclic, O-acylated oxocarbenium ion. The stereoselectivity of the reaction between β-formyl ester 28 and allylsilane 8 is highly dependent on the Lewis acid employed; [25] this is not the case for the reaction of 6, which gives nearly identical trans/cis ratios of γ-lactone 26.…”

Section: Discussionmentioning

confidence: 99%

On the Stereoselectivity of γ-Lactol Substitutions with Allyl- and Propargylsilanes − Synthesis of Disubstituted Tetrahydrofuran Derivatives

Schmitt¹,

Reißig²

2000

Eur. J. Org. Chem.

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Keywords: Carbocations / FelkinϪAnh model / Lewis acids / Silanes / TetrahydrofuranMonosubstituted γ-lactols 1a−1c, 3a−3c and 4a−4c, as well as disubstituted γ-lactol 5 and the γ-hydroxy-substituted γ-lactone 6, were transformed into disubstituted tetrahydrofuran derivatives by treatment with allyl-and propargylsilanes in the presence of Lewis acids. The diastereoselectivities were moderate to excellent and are interpreted by applica-

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Section: Discussionmentioning

confidence: 99%

On the Stereoselectivity of γ-Lactol Substitutions with Allyl- and Propargylsilanes − Synthesis of Disubstituted Tetrahydrofuran Derivatives

Schmitt¹,

Reißig²

2000

Eur. J. Org. Chem.

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“…Submission of 10 to the Luche reduction conditions16 and silyl protection provided 11 , which was hydrolyzed and treated with the allylindium reagent under aqueous Barbier conditions. As anticipated, this carbon‐carbon bond‐forming reaction proceeded via a chelated transition state involving the neighboring carboxyl group,17 and delivered the (9 R ) product 12 very predominantly.…”

Section: The First Synthetic Approach To 5: a Bittersweet Reality Checkmentioning

confidence: 54%

The sclerophytin A adventure

Paquette

2001

The Chemical Record

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The structural designation A originally made by Sharma and Alam to sclerophytin A was considered to be ambiguous and so notably strained relative to B that the latter was targeted for de novo synthesis (Scheme 1). Our two successful routes began with (5S)-(d-menthyloxy)-2(5H)-furanone and involved the application of cycloaddition, Claisen ring expansion, transannular oxymercuration, and 1,2-carbonyl transposition tactics to arrive at B. It was immediately apparent from polarity considerations and spectroscopic data that the antileukemic marine metabolite in question was in need of more deep-seated structural revision. Following close re-examination of an acquired authentic sample by advanced NMR techniques, the strong inference was made that sclerophytin A actually lacked a second oxygen bridge and was in reality the triol C. This conclusion was unequivocally confirmed by diverting an advanced intermediate generated earlier into a short sequence beginning with regiocontrolled dihydroxylation and terminating with configurational inversion at the secondary carbinol center. The status of other members of this series is also presented.

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“…While the carboxylic acid functionality was tolerated in this reaction, the yield was moderate. The lack of regioselectivity observed here can be interpreted to indicate that “chelation control” versus electronic effects are of the same order of magnitude for this substrate . We further broadened the scope of alkyne carboindation reactions by demonstrating the successful allylindation of internal alkynols (entries 11 and 12).…”

Section: Resultsmentioning

confidence: 74%

Carboindation of Carbon−Carbon Triple Bonds: Regioselective Indium-Mediated Allylation of Functionalized Alkynes and Transformation into Halogen-Substituted 1,4-Dienes

Klaps

Schmid

1999

J. Org. Chem.

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By examining the allylindation of a series of substituted alkynes, the relationships between allylindation reactivity and alkyne structure were systematically investigated. While terminal alkynes with protected hydroxyl groups gave the corresponding allylated branched 1,4-dienes (Markovnikov products) within 5-6 h, the unprotected alkynols reacted markedly faster, requiring only 2-4 h of ultrasonication in THF to produce the 1,4-dienols in good yields. In the latter reactions, the regioisomeric outcome was found to depend on the distance between the hydroxyl group and the alkyne moiety: propargylic substrates gave linear 1,4-dienes (anti-Markovnikov products), suggesting the involvement of bicyclic "chelation-controlled" transition state, while 4-pentynol and higher homologues exclusively afforded the branched 1,4-dienes. Moreover, the proposed vinylic R,R-bis-indium intermediates from both protected and unprotected substrates were successfully quenched with N-bromosuccinimide (NBS) and N-iodosuccinimide (NIS) to form tri-and tetrasubstituted dienes in good yields. Taken as a whole, these results illustrate the remarkable stability of the allylindium and vinylindium intermediates despite the presence of protic functionalities in the reaction mixture.

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Stereoselective Indium-Promoted Allylation of γ-Hydroxy-γ-Lactones under Aqueous Conditions. The Neighboring Carboxyl Effect

Cited by 32 publications

References 9 publications

On the Stereoselectivity of γ-Lactol Substitutions with Allyl- and Propargylsilanes − Synthesis of Disubstituted Tetrahydrofuran Derivatives

On the Stereoselectivity of γ-Lactol Substitutions with Allyl- and Propargylsilanes − Synthesis of Disubstituted Tetrahydrofuran Derivatives

The sclerophytin A adventure

Carboindation of Carbon−Carbon Triple Bonds: Regioselective Indium-Mediated Allylation of Functionalized Alkynes and Transformation into Halogen-Substituted 1,4-Dienes

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