Organocatalytic Redox Isomerization of Electron-Deficient Allylic Alcohols: Synthesis of 1,4-Ketoaldehydes

Mondal, Keshab Chandra; Mondal, Buddhadeb; Pan, Subhas Chandra

doi:10.1021/acs.joc.6b00243

Cited by 34 publications

(21 citation statements)

References 42 publications

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“…Accordingly, compound 1a was treated with catalyst I in toluene/D 2 O (16:1), and product d 3 ‐ 2a was isolated as the major diastereomer. Thus, it is expected that at first the tertiary amine moiety of the catalyst undergoes a conjugate addition reaction to 1a to generate 3 , which is subsequently quenched by D 2 O to afford 4 . Enol 5 is then formed by an E2 elimination reaction.…”

Section: Resultsmentioning

confidence: 99%

“…So, the ratedetermining step involves one molecule of 1a and one molecule of catalyst I. We performed a deuterium-incorporation experiment [8] to understand the mechanism of the reaction (Scheme 2). Accordingly, compound 1a was treated with catalyst I in toluene/D 2 O (16:1), and product d 3 -2a was isolated as the major diastereomer.…”

Section: Entrymentioning

confidence: 99%

“…Thus, it is expected that at first the tertiary amine moiety of the catalyst undergoes a conjugate addition reaction to 1a to generate 3, which is subsequently quenched by D 2 O to afford 4. [8] Enol 5 is then formed by an E2 elimination reaction. Tautomerization followed by deuterium abstraction from D 2 O leads to the formation of 2,3-d 2 -6.…”

Section: Entrymentioning

confidence: 99%

“…[7f,7g] We previously reported a method for the organocatalytic redox isomerization of γ-hydroxyenones to 1,4-ketoaldehydes (Scheme 1). [8] In this paper, we report an extraordinary dimerization reaction that proceeds in a highly enantioselective and moderately diastereoselective manner (Scheme 1) with different tertiary amine (thio)urea catalysts (Table 1), [9] and detailed DFT calculations were performed to understand the diastereoselectivity of this reaction.…”

Section: Introductionmentioning

confidence: 99%

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Organocatalytic Asymmetric Dimerization of γ‐Hydroxyenones to Acetals and Theoretical Investigations into the Diastereoselection

Mondal

Satpati

et al. 2017

Eur J Org Chem

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A method for the organocatalytic, highly enantioselective, and moderately diastereoselective dimerization (redox isomerization/acetal formation) of γ‐hydroxyenones is disclosed. The stereogenic acetal products were obtained via hemiacetal intermediates followed by a cyclization reaction. With bifunctional thiourea catalysts, high yields and excellent enantioselectivities were achieved for a variety of acetal products under mild reaction conditions. In addition, detailed DFT calculations were performed to investigate the mechanism of this reaction, and these calculations suggested that the diastereoselectivity was due to a kinetically controlled process.

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Section: Resultsmentioning

confidence: 99%

Section: Entrymentioning

confidence: 99%

Section: Entrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Organocatalytic Asymmetric Dimerization of γ‐Hydroxyenones to Acetals and Theoretical Investigations into the Diastereoselection

Mondal

Satpati

et al. 2017

Eur J Org Chem

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“…1 H NMR data of 6f deduced from the isomeric mixture of 5f/6f agreed with the literature. 16 5-phenyldihydrofuran-2(3H)-one (5f)…”

Section: -Phenyldihydrofuran-2(3h)-one (5f) and 4-oxo-6-phenylbutanal (6f)mentioning

confidence: 99%

From Ring-Expansion to Ring-Contraction: Synthesis of γ-Lactones from Cyclobutanols and Relative Stability of Five- and Six-Membered Endoperoxides toward Organic Bases

Jamey¹,

Ferrié²

2022

Synthesis

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Cyclobutanols undergo a ring expansion with molecular oxygen in the presence of Co(acac)2 to afford 1,2-dioxane-hemiperoxyketals. In the course of acylation, we observed that endoperoxides rearranged into γ-lactone in the presence of triethylamine. Thus, a generalization of this original ring contraction through a Kornblum-DeLaMare rearrangement is here reported. Application of this transformation to monosubstituted 1,2-dioxane derivatives also led to 1,4-ketoaldehydes, in proportions depending on the nature of the substituent. Thisese transformation same conditions applied to 5-membered dioxolane analogs led to fragmentation instead, through a retro-aldol type process. This study emphasizes the difference of stability of 1,2-dioxane and 1,2-dioxolane against organic bases, 1,2-dioxolanes having proved to be particularly reactive whereas 1,2-dioxanes showed a relative tolerance under these conditions.

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redox isomerization

Brannmjk¹

2020

Catalysis From a to Z

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Organocatalytic Redox Isomerization of Electron-Deficient Allylic Alcohols: Synthesis of 1,4-Ketoaldehydes

Cited by 34 publications

References 42 publications

Organocatalytic Asymmetric Dimerization of γ‐Hydroxyenones to Acetals and Theoretical Investigations into the Diastereoselection

Organocatalytic Asymmetric Dimerization of γ‐Hydroxyenones to Acetals and Theoretical Investigations into the Diastereoselection

From Ring-Expansion to Ring-Contraction: Synthesis of γ-Lactones from Cyclobutanols and Relative Stability of Five- and Six-Membered Endoperoxides toward Organic Bases

redox isomerization

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