Organocatalytic Asymmetric α-Allylation and Propargylation of α-Branched Aldehydes with Alkyl Halides

Yoshida, Masanori

doi:10.1021/acs.joc.1c01394

Cited by 6 publications

(3 citation statements)

References 72 publications

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“…Yoshida described the aminocatalytic α-alkylation of branched aldehydes under PTC conditions mainly using allylic and propargylic-type halides and sulfonates [ 64 ]. The reaction was promoted by 30 mol% of the serine-derived amino acid C44 and required as cocatalysts substoichiometric amounts of KI and Bu 4 NI in a water/ tert -butanol mixture ( Scheme 15 ).…”

Section: Methods Based On Enamine Activationmentioning

confidence: 99%

Catalytic Asymmetric α-Functionalization of α-Branched Aldehydes

et al. 2023

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Aldehydes constitute a main class of organic compounds widely applied in synthesis. As such, catalyst-controlled enantioselective α-functionalization of aldehydes has attracted great interest over the years. In this context, α-branched aldehydes are especially challenging substrates because of reactivity and selectivity issues. Firstly, the transient trisubstituted enamines and enolates resulting upon treatment with an aminocatalyst or a base, respectively, would exhibit attenuated reactivity; secondly, mixtures of E- and Z-configured enamines/enolates may be formed; and third, effective face-discrimination on such trisubstituted sp2 carbon intermediates by the incoming electrophilic reagent is not trivial. Despite these issues, in the last 15 years, several catalytic approaches for the α-functionalization of prostereogenic α-branched aldehydes that proceed in useful yields and diastereo- and enantioselectivity have been uncovered. Developments include both organocatalytic and metal-catalyzed approaches as well as dual catalysis strategies for forging new carbon–carbon and carbon–heteroatom (C-O, N, S, F, Cl, Br, …) bond formation at Cα of the starting aldehyde. In this review, some key early contributions to the field are presented, but focus is on the most recent methods, mainly covering the literature from year 2014 onward.

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Section: Methods Based On Enamine Activationmentioning

confidence: 99%

Catalytic Asymmetric α-Functionalization of α-Branched Aldehydes

et al. 2023

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“…An electrostatic interaction between allyl iodide and the carboxylate group assisted the approach of allyl iodide to the Si-face of the enamine to produce (S)-11 a. [39]…”

Section: Nucleophilic Substitution Reactions With Allyl and Propargyl...mentioning

confidence: 99%

“…The steric repulsion between the enamine moiety and the carboxylate group can be avoided when the large side chain (Y) of amino acid is perpendicular to the Re ‐face of the α‐carbon atom of the enamine moiety. An electrostatic interaction between allyl iodide and the carboxylate group assisted the approach of allyl iodide to the Si ‐face of the enamine to produce ( S )‐ 11 a [39] …”

Section: Nucleophilic Substitution Reactions With Allyl and Propargyl...mentioning

confidence: 99%

Asymmetric Synthesis of a Quaternary Carbon Stereogenic Center by Organocatalysis Using a Primary Amino Acid and Its Salt

Yoshida

2023

The Chemical Record

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In this personal account, our recent developments on the asymmetric synthesis of a quaternary carbon stereogenic center by organocatalysis using a primary amino acid and its salt as a catalyst are described in three chapters: (1) conjugate addition to nitroalkenes and vinyl ketones, (2) nucleophilic addition to π‐allyl palladium complexes, and (3) nucleophilic substitution reactions with allyl and propargyl halides. By these methods, asymmetric α‐allylation of α‐branched aldehydes and ketones smoothly proceeded to give γ‐nitroaldehydes, ketoaldehydes, α‐allylated aldehydes, and α‐allylated β‐ketoesters possessing a quaternary carbon stereogenic center in good yields with high enantioselectivities.

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Pd(II)‐Catalyzed Conversion Of N‐Troponyl‐Amino Acid Derivatives Into Cationic Troponyl‐Oxazolidines

Jena,

Sharma

2024

Eur J Org Chem

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Benzoxazole and benzoxazolidine are constituents of various bioactive natural/synthetic molecules comprising benzenoid aromatic residue. However, non‐benzenoid aromatic scaffolds such as tropone and tropolone are also found in natural products. This report describes the synthesis of unusual cationic troponyl‐oxazolidine derivatives from N‐troponyl‐amino acids/peptides by Pd(II)‐catalyzed transformation. X‐ray studies confirm the formation of the first tropylium cation annelated oxazolidine structures and support the formation of unique supramolecular self‐assembly structures owing to the H‐bonding. The CV studies of new tropylium cations reveal their reduction potential ca ‐1.2 V. Hence, cationic troponyl‐oxazolidinyl amino acids/peptides could be promising analogs of benzoxazolidine for the development of therapeutic drugs.

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Organocatalytic Asymmetric α-Allylation and Propargylation of α-Branched Aldehydes with Alkyl Halides

Cited by 6 publications

References 72 publications

Catalytic Asymmetric α-Functionalization of α-Branched Aldehydes

Catalytic Asymmetric α-Functionalization of α-Branched Aldehydes

Asymmetric Synthesis of a Quaternary Carbon Stereogenic Center by Organocatalysis Using a Primary Amino Acid and Its Salt

Pd(II)‐Catalyzed Conversion Of N‐Troponyl‐Amino Acid Derivatives Into Cationic Troponyl‐Oxazolidines

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