Catalytic, Enantioselective N-Acylation of Lactams and Thiolactams Using Amidine-Based Catalysts

Yang, Xing; Bumbu, Valentina D.; Liu, Peng; Li, Ximin; Jiang, Hui; Uffman, Eric W.; Guo, Lei; Zhang, Wei; Jiang, Xuntian; Houk, K. N.; Birman, Vladimir B.

doi:10.1021/ja306766n

Cited by 69 publications

(40 citation statements)

References 79 publications

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“…The efficacy of these catalysts has been demonstrated in the acylative kinetic resolution of secondary alcohols, [62] oxazolidinones, [63] and lactams (Scheme 18A). [64] These catalysts have also been employed for dynamic kinetic resolution (DKR) of azlactones en route to natural and unnatural α-amino esters (Scheme 18B). [65] …”

Section: Catalyst–substrate Cation–π Interactionsmentioning

confidence: 99%

The Cation–π Interaction in Small‐Molecule Catalysis

2016

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Catalysis by small molecules (≤ 1000 Da, 10−9 m) capable of binding and activating substrates via attractive, noncovalent interactions has emerged as an important approach in organic and organometallic chemistry. While the canonical noncovalent interactions—including hydrogen-bonding, ion-pairing, and π-stacking—have become mainstays of catalyst design, the cation–π interaction has been comparatively underutilized in this context since its discovery in the 1980s. However, like a hydrogen bond, the cation–π interaction exhibits a typical binding affinity of several kcal/mol with substantial directionality. These properties render it attractive as a design element for the development of small-molecule catalysts, and in recent years, the catalysis community has begun to take advantage of these features, drawing inspiration from pioneering research in molecular recognition and structural biology. This review surveys the burgeoning application of the cation–π interaction in catalysis.

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Section: Catalyst–substrate Cation–π Interactionsmentioning

confidence: 99%

The Cation–π Interaction in Small‐Molecule Catalysis

2016

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“…Cation-π effects have been found to govern the acyl transfer-mediated kinetic resolution of lactams and thiolactams with amidine catalysts. 7 Despite the widespread importance of amine acylation reactions, the precise details of the mechanism of the kinetic resolution of unactivated amines have never been fully elucidated, reflecting a fundamental gap in the literature.…”

Section: Introductionmentioning

confidence: 99%

Concerted Amidation of Activated Esters: Reaction Path and Origins of Selectivity in the Kinetic Resolution of Cyclic Amines via N-Heterocyclic Carbenes and Hydroxamic Acid Cocatalyzed Acyl Transfer

et al. 2014

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The N-heterocyclic carbene and hydroxamic acid cocatalyzed kinetic resolution of cyclic amines generates enantioenriched amines and amides with selectivity factors up to 127. In this report, a quantum mechanical study of the reaction mechanism indicates that the selectivity-determining aminolysis step occurs via a novel concerted pathway in which the hydroxamic acid plays a key role in directing proton transfer from the incoming amine. This modality was found to be general in amide bond formation from a number of activated esters including those generated from HOBt and HOAt, reagents that are broadly used in peptide coupling. For the kinetic resolution, the proposed model accurately predicts the faster reacting enantiomer. A breakdown of the steric and electronic control elements shows that a gearing effect in the transition state is responsible for the observed selectivity.

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Section: Catalysis By Nucleofugal Group Substitutionmentioning

confidence: 99%

“…Several enantiomerically pure amidine, isothiourea and guadinine derivatives have been prepared and tested for their ability to catalyze enantioselective acyl transfers as shown first by Birman and co-workers in 2004 [108]. Examples are given in Figure 8 [109,110]. led to the development of enantiomerically pure phosphines that catalyze enantioselective acyl transfers [97][98][99][100][101].…”

Section: N-heterocyclic Carbene-catalyzed Transesterificationsmentioning

confidence: 99%

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

et al. 2016

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Catalysis fulfills the promise that high-yielding chemical transformations will require little energy and produce no toxic waste. This message is carried by the study of the evolution of molecular catalysis of some of the most important reactions in organic chemistry. After reviewing the conceptual underpinnings of catalysis, we discuss the applications of different catalysts according to the mechanism of the reactions that they catalyze, including acyl group transfers, nucleophilic additions and substitutions, and C-C bond forming reactions that employ umpolung by nucleophilic additions to C=O and C=C double bonds. We highlight the utility of a broad range of organocatalysts other than compounds based on proline, the cinchona alkaloids and binaphthyls, which have been abundantly reviewed elsewhere. The focus is on organocatalysts, although a few examples employing metal complexes and enzymes are also included due to their significance. Classical Brønsted acids have evolved into electrophilic hands, the fingers of which are hydrogen donors (like enzymes) or other electrophilic moieties. Classical Lewis base catalysts have evolved into tridimensional, chiral nucleophiles that are N-(e.g., tertiary amines), P-(e.g., tertiary phosphines) and C-nucleophiles (e.g., N-heterocyclic carbenes). Many efficient organocatalysts bear electrophilic and nucleophilic moieties that interact simultaneously or not with both the electrophilic and nucleophilic reactants. A detailed understanding of the reaction mechanisms permits the design of better catalysts. Their construction represents a molecular science in itself, suggesting that sooner or later chemists will not only imitate Nature but be able to catalyze a much wider range of reactions with high chemo-, regio-, stereo-and enantioselectivity. Man-made organocatalysts are much smaller, cheaper and more stable than enzymes.

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Catalytic, Enantioselective N-Acylation of Lactams and Thiolactams Using Amidine-Based Catalysts

Cited by 69 publications

References 79 publications

The Cation–π Interaction in Small‐Molecule Catalysis

The Cation–π Interaction in Small‐Molecule Catalysis

Concerted Amidation of Activated Esters: Reaction Path and Origins of Selectivity in the Kinetic Resolution of Cyclic Amines via N-Heterocyclic Carbenes and Hydroxamic Acid Cocatalyzed Acyl Transfer

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

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