Functionalized cyclopentanes via Sc(III)-catalyzed intramolecular enolate alkylation

McAtee, Christopher C.; Ellinwood, Duncan C.; McAtee, Rory C.; Schindler, Corinna S.

doi:10.1016/j.tet.2018.04.036

Cited by 8 publications

(8 citation statements)

References 27 publications

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“…The ability of a Lewis acid (LA) to activate 1,3-dicarbonyls through the formation of metallic enolates was recently explored by Schindler’s group for the intramolecular tert -alkylation of prenylated β-keto esters 103 ( Scheme 39A ) [ 122 ]. Cyclopentanes 104 containing two vicinal quaternary carbon centers were synthetized in yields of up to 90% under scandium triflate (Sc(OTf) 3 ) catalysis.…”

Section: Reviewmentioning

confidence: 99%

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Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

Silva¹,

Coelho²

2021

Beilstein J. Org. Chem.

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Olefin double-bond functionalization has been established as an excellent strategy for the construction of elaborate molecules. In particular, the hydroalkylation of olefins represents a straightforward strategy for the synthesis of new C(sp3)–C(sp3) bonds, with concomitant formation of challenging quaternary carbon centers. In the last 20 years, numerous hydroalkylation methodologies have emerged that have explored the diverse reactivity patterns of the olefin double bond. This review presents examples of olefins acting as electrophilic partners when coordinated with electrophilic transition-metal complexes or, in more recent approaches, when used as precursors of nucleophilic radical species in metal hydride hydrogen atom transfer reactions. This unique reactivity, combined with the wide availability of olefins as starting materials and the success reported in the construction of all-carbon C(sp3) quaternary centers, makes hydroalkylation reactions an ideal platform for the synthesis of molecules with increased molecular complexity.

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Section: Reviewmentioning

confidence: 99%

“… A) Sc(OTf) 3 -mediated carbocyclization approach for the synthesis of vicinal quaternary carbon centers. B) Proposed reaction mechanism (Schindler (2018) [ 122 ]). …”

Section: Reviewmentioning

confidence: 99%

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

Silva¹,

Coelho²

2021

Beilstein J. Org. Chem.

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“…Interestingly, olefins functionalized with adamantyl groups afforded cyclopentadienes in generally higher yields (57–86%). This may occur due, in part, to the increased sterics of the adamantyl group suppressing competing intramolecular-enolate alkylation . Additional elements of unsaturation present in the substrate were compatible with the optimized reaction conditions, resulting in the formation of alkene 39 in 81% yield.…”

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confidence: 90%

Catalytic, Interrupted Carbonyl-Olefin Metathesis for the Formation of Functionalized Cyclopentadienes

et al. 2023

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Cyclopentadienes are scaffolds in organometallic chemistry, synthetic organic chemistry, and catalysis. We herein describe a regioselective Lewis-acid-catalyzed method for the synthesis of highly functionalized cyclopentadienes incorporating electronically and sterically diverse subunits. Our experimental and theoretical investigations support a mechanism that is related to catalytic carbonyl-olefin metathesis reactions wherein Lewis-acid-catalyzed cycloadditions between carbonyl and alkene functionalities afford reactive oxetane intermediates. However, in lieu of a [2+2]-cycloreversion, stepwise oxetane fragmentation to intermediate carbocations results in the formation of functionalized cyclopentadienes via interrupted carbonyl-olefin metathesis. This work provides insights into the design of catalytic carbonyl-olefin metathesis reactions of aliphatic ketone substrates as stepwise oxetane fragmentation was previously only reported as a competing reaction pathway for aryl ketones.

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“…With access to 9 a/9 b secured, we proceeded to the intramolecular carbonyl a-tert-alkylation (Table 1). At this stage, we considered three distinct tactics to achieve this challenging transformation: 1) Brønsted or Lewis acid-mediated cationic cyclization; [8,9] 2) photocatalyzed radical cyclization; [10] 3) Mn(OAc) 3 -mediated oxidative cyclization. [11] Disappointedly, numerous studies with 9 a/9 b proved unfruitful and mainly led to decomposition into unidentified side products (entries 1-4).…”

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confidence: 99%

Enantioselective Total Synthesis of Berkeleyone A and Preaustinoids

Zhang

Franzoni³

et al. 2021

Angew Chem Int Ed

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Herein we report the first enantioselective total synthesis of 3,5‐dimethylorsellinic acid‐derived meroterpenoids (−)‐berkeleyone A and its five congeners ((−)‐preaustinoids A, A1, B, B1, and B2) in 12–15 steps, starting from commercially available 2,4,6‐trihydroxybenzoic acid hydrate. Based upon the recognition of latent symmetry within D‐ring, our convergent synthesis features two critical reactions: 1) a symmetry‐breaking, diastereoselective dearomative alkylation to assemble the entire carbon core, and 2) a Sc(OTf)3‐mediated sequential Krapcho dealkoxycarbonylation/carbonyl α‐tert‐alkylation to forge the intricate bicyclo[3.3.1]nonane framework. We also conducted our preliminary biomimetic investigations and uncovered a series of rearrangements (α‐ketol, α‐hydroxyl‐β‐diketone, etc.) responsible for the biomimetic diversification of (−)‐berkeleyone A into its five preaustinoid congeners.

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Functionalized cyclopentanes via Sc(III)-catalyzed intramolecular enolate alkylation

Cited by 8 publications

References 27 publications

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

Catalytic, Interrupted Carbonyl-Olefin Metathesis for the Formation of Functionalized Cyclopentadienes

Enantioselective Total Synthesis of Berkeleyone A and Preaustinoids

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