Dictating Thermodynamic Control through Tethering: Applications to Stereoselective Bis‐Spiroketal Synthesis

Asari, Austin H.; Floreancig, Paul E.

doi:10.1002/anie.201916270

Cited by 9 publications

(6 citation statements)

References 55 publications

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“…As shown in Scheme A, preparation of 4a started with Grignard reaction of aldehyde 5 with 3-butenylmagnesium bromide to give alcohol 6 . Cleavage of the double bond followed by Wittig reaction of the derived hemiacetal with Ph 3 P + EtBr – / n -BuLi delivered hydroxy olefin 4a in 81% yield with Z / E 3:1 selectivity.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The synthesis of olefin 54 started with regioselective ring opening of epoxy alcohol 59, prepared via Sharpless asymmetric epoxidation 32 of trans-2-hepten-1-ol (Ti(Oi-Pr) 4 , (+)-DET, t-BuOOH, 4 Å MS, CH 2 Cl 2 , 84%, 94% ee), 33 10). Asymmetric reduction of the ketone carbonyl group using (S)-2-Me-CBS oxazaborolidine/BH 3 •THF 35 delivered allylic alcohol 64 in 90% yield with greater than 20:1 diastereoselectivity.…”

Section: ■ Introductionmentioning

confidence: 99%

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Cobalt-Catalyzed Hartung–Mukaiyama Cyclization of γ-Hydroxy Olefins: Stereocontrolled Synthesis of the Tetrahydrofuran Moiety of Amphidinolide N

et al. 2021

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Cobalt-catalyzed Mukaiyama-type cyclization of γ-hydroxy olefins is known as an atom-and step-economical means for stereoselective synthesis of 2,5-trans-substituted tetrahydrofuran derivatives. In this study, we investigated the synthesis of a series of 2,5-substituted tetrahydrofuran derivatives by means of a cobalt-catalyzed Hartung−Mukaiyama cyclization. The stereochemical consequence of the reaction was found to be largely dependent on the substitution pattern and relative configuration of γ-hydroxy olefins. 2,5-cis-Substituted tetrahydrofuran derivatives could be obtained diastereoselectively from appropriately substituted γ-hydroxy olefins. Additionally, relatively bulky olefin substituents and unprotected hydroxy groups at non-interfering positions (e.g., α and δ) were well tolerated in the reaction. Finally, the synthetic versatility of the Hartung−Mukaiyama cyclization was demonstrated through a stereocontrolled synthesis of the tetrahydrofuran moiety of amphidinolide N, a potent cytotoxic macrolide of marine origin. This study expands the capacity of Mukaiyama-type cyclization in that it can be used in convergent assembly of complex tetrahydrofuran motifs from internal olefins.

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Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Cobalt-Catalyzed Hartung–Mukaiyama Cyclization of γ-Hydroxy Olefins: Stereocontrolled Synthesis of the Tetrahydrofuran Moiety of Amphidinolide N

et al. 2021

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“…19 The strategy proved to be highly successful, with macrodilactone 29 cyclizing in the presence of Re2O7•SiO2 to yield 30 as a single stereoisomer. 20 The catalyst for this reaction is prepared by a simple adsorption of Re2O7 onto SiO2 in solution followed by solvent removal, leading to a 10% m/m loading. 21 delivering Re2O7, which leeches from the solid support to promote the reactions.…”

Section: Methodsmentioning

confidence: 99%

“…19 The strategy proved to be highly successful, with macrodilactone 29 cyclizing in the presence of Re 2 O 7 •SiO 2 to yield 30 as a single stereoisomer. 20 The catalyst for this reaction is prepared by simple adsorption of Re 2 O 7 onto SiO 2 in solution, followed by solvent removal, leading to a 10 mass% loading. 21 This variant of the catalyst is very useful for small-scale reactions and for conducting reactions on humid days, because Re 2 O 7 readily adsorbs atmospheric water, leading to slower reactions.…”

Section: Account Synlettmentioning

confidence: 99%

Perrhenate Esters as Intermediates in Molecular Complexity-Increasing Reactions

Floreancig¹

2021

Synlett

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Allylic alcohols form perrhenate esters upon reaction with Re2O7 or HOReO3. These species undergo non-stereospecific and non-regiospecific alcohol transposition reactions through cationic intermediates. Sequencing these non-selective processes with reversible trapping by electrophiles results in cyclization reactions where regio- and stereocontrol are dictated by thermodynamics. The cationic intermediates can also be utilized as electrophiles in intra- or intermolecular dehydrative reactions with nucleophiles. These processes serve as the basis for applications to the catalytic syntheses of a wide range of heterocyclic and carbocyclic structures that often show high increases of molecular complexity. This Account describes the sequence of events that started from a need to solve a problem for the completion of a natural product synthesis and evolved into a central element in the design of numerous new transformations that proceed under mild conditions from readily accessible substrates.

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“…The structures of these isomers, which differ in the stereochemical orientations of their peripheral tetrahydrofuran rings, were determined based on extensive 1 H and 13 C NMR analyses and a crystal structure of 16. [12,13] The ability to control the stereochemical orientation of the central tetrahydrofuran ring is unprecedented for this ring system. [6] Exposing either 15 or 16 to Re 2 O 7 ·SiO 2 regenerated the 1:1 mixture that was observed in the cyclization, indicating that the product ratio is due to thermodynamic, rather than kinetic, control.…”

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confidence: 99%