Oxidative cyclization of γ-alkylidene butenolides. Stereoselective preparation of spirolactones

Fernández, Raquel Galán; Clemente-Tejeda, David; Bermejo, Francisco

doi:10.3998/ark.5550190.0013.915

Cited by 7 publications

(1 citation statement)

References 8 publications

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“…9 However, the preparation of appropriate starting materials for these pathways is often tedious and necessitates the use of protecting groups. On the other hand, haloetherification 2 b ,10 or olefination 11 of γ-alkylidene butenolides also affords the target motif, albeit only in moderate to good yields. A straightforward method that is anchored on more readily available or easily prepared precursors would be preferable and would provide a simpler platform to rapidly assemble oxaspirolactones or natural products thereof in ideally quantitative yields.…”

Section: Introductionmentioning

confidence: 99%

Direct synthesis of oxaspirolactones in batch, photoflow, and silica gel-supported solvent-free conditionsviavisible-light photo- and heterogeneous Brønsted acid relay catalysis

Miñoza

et al. 2022

Green Chem.

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Section: Introductionmentioning

confidence: 99%

Direct synthesis of oxaspirolactones in batch, photoflow, and silica gel-supported solvent-free conditionsviavisible-light photo- and heterogeneous Brønsted acid relay catalysis

Miñoza

et al. 2022

Green Chem.

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Titanocene(III) Chloride Mediated Stereoselective Synthesis of Trisubstituted Tetrahydrofurans and a Spirolactone by Tandem Radical Reactions

Mukherjee¹,

Roy²,

Roy³

2014

Eur J Org Chem

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The titanocene(III) chloride (Cp2TiCl) mediated stereoselective synthesis of highly substituted tetrahydrofurans has been achieved by a reaction that proceeds through a tandem radical cyclization reaction between a Baylis–Hillman adduct and an activated bromo/iodo compound. The reaction of an epoxide with the Baylis–Hillman adduct furnished a spirolactone through a radical cyclization followed by an in situ lactonization. Cp2TiCl was prepared in situ from commercially available Cp2TiCl2 and zinc dust in tetrahydrofuran.

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Enantioselective total syntheses of (+)-stemofoline and three congeners based on a biogenetic hypothesis

2020

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The powerful insecticidal and multi-drug-resistance-reversing activities displayed by the stemofoline group of alkaloids render them promising lead structures for further development as commercial agents in agriculture and medicine. However, concise, enantioselective total syntheses of stemofoline alkaloids remain a formidable challenge due to their structural complexity. We disclose herein the enantioselective total syntheses of four stemofoline alkaloids, including (+)-stemofoline, (+)-isostemofoline, (+)-stemoburkilline, and (+)-(11S,12R)-dihydrostemofoline, in just 19 steps. Our strategy relies on a biogenetic hypothesis, which postulates that stemoburkilline and dihydrostemofolines are biogenetic precursors of stemofoline and isostemofoline. Other highlights of our approach are the use of Horner–Wadsworth–Emmons reaction to connect the two segments of the molecule, an improved protocol allowing gram-scale access to the tetracyclic cage-type core, and a Cu-catalyzed direct and versatile nucleophilic alkylation reaction on an anti-Bredt iminium ion. The synthetic techniques that we developed could also be extended to the preparation of other Stemona alkaloids.

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Oxidative cyclization of γ-alkylidene butenolides. Stereoselective preparation of spirolactones

Abstract: A new route to 1,6-dioxaspiro[4.4]non-3-en-2-ones is established by bromoetherification of dihydroxybutenolides. An asymmetric total synthesis of 8-epi-crassalactone D starting from methyl cinnamate has been accomplished.

Cited by 7 publications

References 8 publications

Direct synthesis of oxaspirolactones in batch, photoflow, and silica gel-supported solvent-free conditionsviavisible-light photo- and heterogeneous Brønsted acid relay catalysis

Direct synthesis of oxaspirolactones in batch, photoflow, and silica gel-supported solvent-free conditionsviavisible-light photo- and heterogeneous Brønsted acid relay catalysis

Titanocene(III) Chloride Mediated Stereoselective Synthesis of Trisubstituted Tetrahydrofurans and a Spirolactone by Tandem Radical Reactions

Enantioselective total syntheses of (+)-stemofoline and three congeners based on a biogenetic hypothesis

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