Mechanistic insights into entropy-driven 1,2-type Friedel-Crafts reaction with conformationally flexible guanidine-bisthiourea bifunctional organocatalysts

Nakano, Katsuhiro; Orihara, Tatsuya; Kawaguchi, Masaki; Hosoya, Keisuke; Hirao, Shogo; Tsutsumi, Ryosuke; Yamanaka, Masahiro; Odagi, Minami; Nagasawa, Kazuo

doi:10.1016/j.tet.2021.132281

Cited by 11 publications

(2 citation statements)

References 40 publications

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“…It is noteworthy that the concept of entropy-driven phenomena is already known and appears frequently in various branches of materials science and chemistry. We may document it by entropy-driven processes such as the Friedel-Crafts reaction [12], electrochemiluminescence [13], supramolecular polymerization [14], nanocrystal stability [15] and adsorption [16]. In fact, entropy-driven interfacial segregation was recently reported [17], although "segregation" was considered to have a different meaning to that in this paper.…”

Section: Indirect Support Of Entropy-driven Grain Boundary Segregationmentioning

confidence: 66%

Entropy-Driven Grain Boundary Segregation: Prediction of the Phenomenon

Lejček

Hofmann

2021

Metals

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The question is formulated as to whether entropy-driven grain boundary segregation can exist. Such a phenomenon would be based on the assumption that a solute can segregate at the grain boundary sites that exhibit positive segregation energy (enthalpy) if the product of segregation entropy and temperature is larger than this energy (enthalpy). The possibility of entropy-driven grain boundary segregation is discussed for several model examples in iron-based systems, which can serve as indirect evidence of the phenomenon. It is shown that entropy-driven grain boundary segregation would be a further step beyond the recently proposed entropy-dominated grain boundary segregation as it represents solute segregation at “anti-segregation” sites.

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Section: Indirect Support Of Entropy-driven Grain Boundary Segregationmentioning

confidence: 66%

Entropy-Driven Grain Boundary Segregation: Prediction of the Phenomenon

Lejček

Hofmann

2021

Metals

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“…In this context, the guanidinium cation is a promising candidate, since it is a strong hydrogen-bond donor and is stable under oxidizing conditions. , We have recently developed a series of guanidinium-bis(thio)urea bifunctional organocatalysts and have employed them for various asymmetric reactions (Figure b). , These catalysts contain multiple hydrogen-bond donors that can interact with nucleophiles and electrophiles, and promote the reaction via a synergistic proximity effect. − Given the potential for hydrogen bonding with β-dicarbonyl compounds, we envisioned that these catalysts might also be effective for the asymmetric coupling reaction of 2-oxindole-derived β-keto esters mediated by hypoiodite (Figure c).…”

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confidence: 99%

Enantioselective Oxidative Enolate Coupling of Oxindoles Catalyzed by Chiral Guanidinium Hypoiodite

et al. 2023

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Hypoiodite is an environmentally friendly oxidant that has been developed to drive a variety of bond-forming reactions. Recently, asymmetric oxidative bond-forming reactions using hypoiodite in the presence of chiral onium organocatalysts have been used to synthesize carbon−heteroatom bonds, but asymmetric carbon−carbon bond-forming reactions have not been reported. Herein, we present an oxidative enolate coupling reaction of oxindoles to provide optically active oxindole dimers bearing consecutive all-carbon quaternary stereogenic centers, using a chiral guanidinium hypoiodite catalyst. This reaction affords the corresponding homocoupling products with high enantioselectivity. We also describe oxidative enolate cross-coupling reactions of two oxindoles bearing electronically distinct substituents.

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Enantioselective Vinylogous Mannich Reaction of Acyclic Vinylketene Silyl Acetals with Acyclic Ketimines

et al. 2021

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The first enantioselective vinylogous Mannich reaction of acyclic vinylketene silyl acetals with acyclic ketimines derived from alkynyl ketoesters was developed. Excellent yields and enantioselectivities were obtained from the reaction using bis(imidazoline)‐Zn(II) catalyst. Based on experiments and MO calculation, a plausible transition state was proposed to explain the stereoselectivity of the reaction. The obtained products were converted into various amines and a lactam. This process provides an efficient route for the synthesis of acyclic δ‐amino‐α,β‐unsaturated carbonyl compounds and their derivatives.

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Mechanistic insights into entropy-driven 1,2-type Friedel-Crafts reaction with conformationally flexible guanidine-bisthiourea bifunctional organocatalysts

Cited by 11 publications

References 40 publications

Entropy-Driven Grain Boundary Segregation: Prediction of the Phenomenon

Entropy-Driven Grain Boundary Segregation: Prediction of the Phenomenon

Enantioselective Oxidative Enolate Coupling of Oxindoles Catalyzed by Chiral Guanidinium Hypoiodite

Enantioselective Vinylogous Mannich Reaction of Acyclic Vinylketene Silyl Acetals with Acyclic Ketimines

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