Enantioselective synthesis of chiral oxazolines from unactivated ketones and isocyanoacetate esters by synergistic silver/organocatalysis

Martínez‐Pardo, Pablo; Blay, Gonzalo; Muñoz, M. Carmen; Pedro, José R.; Sanz‐Marco, Amparo; Vila, Carlos

doi:10.1039/c8cc00856f

Cited by 25 publications

(11 citation statements)

References 32 publications

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“…London dispersion interactions between sterically demanding DTBM P‐substituents and the aromatic ring of the aldehyde may also contribute to the stereoselectivity. These mechanistic features are in accord with the hydrogen‐bonding mechanism proposed for the silver/squaramide‐based organocatalyst hybrid system, [3o,p] and might encourage the reconsideration of proposed mechanisms of other catalyst systems for isocyanoacetate aldol reactions [3] and related metal/organocatalyst hybrid systems [2b,11] . Further catalyst and reaction development based on the information obtained in this study is underway.…”

Section: Methodssupporting

confidence: 79%

Silver‐Catalyzed Asymmetric Aldol Reaction of Isocyanoacetic Acid Derivatives Enabled by Cooperative Participation of Classical and Nonclassical Hydrogen Bonds

et al. 2022

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The silver‐catalyzed asymmetric aldol reaction of isocyanoacetic acid derivatives with aldehydes has been developed by employing a chiral prolinol‐phosphine as a hydrogen‐bond‐donating P,N,O ligand. DFT calculations indicated that the reaction proceeds in a stepwise manner, involving C−C bond forming carbonyl addition and subsequent enantioselectivity‐determining oxazoline ring formation. An O−H⋅⋅⋅O/sp3‐C−H⋅⋅⋅O two‐point hydrogen bond donated by the prolinol moiety of the ligand activates the aldehyde in the C−C bond formation step and facilitates the subsequent cyclization under stereocontrol by the catalyst. The calculations further suggest that additional nonclassical C−H⋅⋅⋅O hydrogen bonds as well as London dispersion interactions may also participate synergistically in the stereocontrol.

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Section: Methodssupporting

confidence: 79%

Silver‐Catalyzed Asymmetric Aldol Reaction of Isocyanoacetic Acid Derivatives Enabled by Cooperative Participation of Classical and Nonclassical Hydrogen Bonds

et al. 2022

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“…After extensive optimization, they found that the combination of a bifunctional Brønsted base‐squaramide 17 b (5 mol %) with Ag 2 O (2.5 mol %) effectively promoted the reaction of various aryl‐alkyl and alkyl‐alkyl ketones with isocyanoacetates 1 , forming a range of cis ‐4‐carboxyl‐2‐oxazolines 21 in high yields with moderate to good excellent diastereoselectivities and excellent enantioselectivities (Scheme 5 c). [33] The result of this method contrasted with that described by Dixon and co‐workers, who obtained the trans ‐oxazolines 21 as the major product. Therefore, these two methods are complementary to each other.…”

Section: [3+2] Cycloaddition Reactions Of Isocyanides With Polarized mentioning

confidence: 59%

Catalytic Enantioselective Isocyanide‐Based Reactions: Beyond Passerini and Ugi Multicomponent Reactions

Luo

Chen

et al. 2021

Chemistry A European J

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The development of catalytic enantioselective isocyanide‐based reactions is currently of great interest because the resulting products are valuable in organic synthesis, pharmacological chemistry, and materials science. This review assembles and comprehensively summarizes the recent achievements in this rapidly growing area according to the reaction types. Special attention is paid to the advantages, limitations, possible mechanisms, and synthetic applications of each reaction. In addition, a personal outlook on the opportunities for further exploration is given at the end.

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“…The same research group also showed the application of Ag + /squaramide cooperative catalysis in (3 + 2) annulation between isocyanoacetate 260 and simple ketones 326 in course of preparing chiral oxazolines 327 bearing two contiguous stereocenters. [133] Several acetophenone derivatives containing both electron donating and withdrawing substituents in the aryl ring reacted with different alkyl isocyano acetates to deliver the products with high chemical yields, poor to excellent cis/ trans selectivities and excellent enantiocontrol for both diastereoisomers. Diastereoselectivity increases markedly with increase in steric bulk of the alkyl substituent in the ketone and only few examples were presented involving alkyl, alkyl ketones (Scheme 87a).…”

Section: Synthesis Of Heterocycles Containing N and Omentioning

confidence: 99%

Squaramide Catalyzed Asymmetric Synthesis of Five‐ and Six‐Membered Rings

Biswas¹,

Ghosh

Shankhdhar

et al. 2021

Asian J Org Chem

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Chiral analogues of squaramides have been fruitful in organocatalyzed asymmetric reactions over last decade. Alongside other H-bonding catalysts like ureas, thioureas: squaramides have been proved to be efficient asymmetric catalysts for the formation of acyclic and cyclic chiral molecules. A wide range of cyclic molecules bearing multiple functionalities and stereocenters have been synthesized by using several bifunctional squaramides as catalysts. These catalysts perform as base utilizing basic N atom in their chiral extension and help in stereoinduction by forming H-bonds with suitable H-bond acceptors. The present review focuses on assembling recent progresses of asymmetric synthesis of five and six membered rings promoted by squaramides. A handful of articles have been published by several research groups documenting asymmetric construction of five-and six-membered rings as part of interesting and complex molecular architectures. Different methodologies like conventional and formal cycloadditions or cascade reactions have been engineered through the assistance of chiral squaramides to fabricate the carbo-and heterocycles. This review also includes dual and cooperative catalytic system in which squaramide is one of the catalysts.

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Enantioselective synthesis of chiral oxazolines from unactivated ketones and isocyanoacetate esters by synergistic silver/organocatalysis

Cited by 25 publications

References 32 publications

Silver‐Catalyzed Asymmetric Aldol Reaction of Isocyanoacetic Acid Derivatives Enabled by Cooperative Participation of Classical and Nonclassical Hydrogen Bonds

Silver‐Catalyzed Asymmetric Aldol Reaction of Isocyanoacetic Acid Derivatives Enabled by Cooperative Participation of Classical and Nonclassical Hydrogen Bonds

Catalytic Enantioselective Isocyanide‐Based Reactions: Beyond Passerini and Ugi Multicomponent Reactions

Squaramide Catalyzed Asymmetric Synthesis of Five‐ and Six‐Membered Rings

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