Chiral Cyclopropenimine‐catalyzed Asymmetric Michael Addition of Bulky Glycine Imine to α,β‐Unsaturated Isoxazoles DOI
Yu‐Jun Bai,

Mei‐Ling Cheng,

Xiaohui Zheng

et al.

Chemistry - An Asian Journal, Journal Year: 2022, Volume and Issue: 17(11)

Published: April 12, 2022

A highly efficient asymmetric Michael addition of bulky glycine imine to α,β-unsaturated isoxazoles has been achieved by using 5 mol% chiral cyclopropenimine as a organo-superbase catalyst under mild conditions. adducts were obtained in excellent yields (up 97%) and stereoselectivities >99 : 1 dr 98% ee). significant solvent effect was found these organosuperbase catalyzed reactions. Gram-scale preparation their transformations are realized provide corresponding products without loss stereoselectivities. The configurations adduct determined single-crystal X-ray diffraction analysis.

Language: Английский

Proton-triggered topological transformation in superbase-mediated selective polymerization enables access to ultrahigh-molar-mass cyclic polymers DOI
Li Zhou, Liam T. Reilly, Changxia Shi

et al.

Nature Chemistry, Journal Year: 2024, Volume and Issue: 16(8), P. 1357 - 1365

Published: April 22, 2024

Language: Английский

Citations

17
Compact Rotaxane Superbases DOI Creative Commons
M. Power, David T. J. Morris, Íñigo J. Vitórica‐Yrezábal

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(15), P. 8593 - 8599

Published: April 11, 2023

Challenges for the development of efficacious new superbases include their ease synthesis, chemical stability, and high basicity, while minimizing nucleophilicity is important reducing unwanted side reactions. Here, we introduce a family organic superbases, compact amine-crown ether rotaxanes, which show desirable characteristics in all these respects. Metal-free active template synthesis provides access to range rotaxanes with as little three atoms between stoppering groups, locking location small crown (21C7 24C8 derivatives) over amine group axle. The forced proximity interlocked protophilic components results pKaH+ values 32.2 acetonitrile, up 13 units greater than non-interlocked components, brings free base into basicity realm phosphazene superbases. rotaxane are generally chemically stable and, model reaction eliminate HBr from primary alkyl bromide complete selectivity deprotonation alkylation. Their modest size, low nucleophilicity, best cases, rapid substrate kinetics excellent hydrolytic stability make intriguing candidates potential applications supramolecular materials chemistry.

Language: Английский

Citations

22
Potential Push-Pull Carbon Superbases Based on Methyl Substitution of Rare Tautomers of Imines DOI Creative Commons
Ewa D. Raczyńska, J. Gál, Pierre‐Charles Maria

et al.

Molecules, Journal Year: 2025, Volume and Issue: 30(3), P. 474 - 474

Published: Jan. 22, 2025

Push-pull imines with strong electron donor group(s) display exceptional basicity in the gas phase. Most of them do not exhibit prototropic tautomerism, and gas-phase acid-base equilibria have been already well described reviewed. Some questions remain for tautomeric systems, particularly their uncommon forms. As shown by quantum-chemical calculations, some often-neglected tautomers higher than thermodynamically favored However, participation mixtures being equilibrium is negligible, can be impossible to measure phase method. During this work, we examined proton acyclic cyclic push-pull organic bases containing amidine or guanidine group. By confirmed existence very low amounts rare forms, particular, those bearing a methylidene (=CH2) We also demonstrated that alkyl derivatives tautomers, free prototropy, good candidates as C bases, i.e., protonated on =CH2

Language: Английский

Citations

1
Triazabicyclodecene: A versatile catalyst for polymer synthesis DOI Open Access
Jeung Gon Kim, Gue Seon Lee, Anna Lee

et al.

Journal of Polymer Science, Journal Year: 2023, Volume and Issue: 62(1), P. 42 - 91

Published: Nov. 3, 2023

Abstract This comprehensive review aims to provide an in‐depth analysis of the catalytic performance 1,5,7‐triazabicyclo[4,4,0]dec‐5‐ene (TBD) in polymer synthesis. TBD, a well‐established organic superbase, possesses distinctive bifunctional character that grants it exceptional capabilities, particularly processes such as transesterification or transamidation. TBD has garnered considerable attention since its initial report by Hedrick and Waymouth 2006, played pivotal role diverse polymerization reactions. Its versatility spans various modes, including chain‐growth step‐growth polymerization, post‐polymerization modification, network thermoset formation. More recently, utility extended green chemical recycling polymers. By providing encompassing overview TBD's historical journey, this delves into past accomplishments while shedding light on present future potential organocatalysts science.

Language: Английский

Citations

16
Intramolecular chaperone-assisted dual-anchoring activation (ICDA): a suitable preorganization for electrophilic halocyclization DOI Creative Commons
Xihui Yang,

Haowei Gao,

Jiale Yan

et al.

Chemical Science, Journal Year: 2024, Volume and Issue: 15(16), P. 6130 - 6140

Published: Jan. 1, 2024

The halocyclization reaction represents one of the most common methodologies for synthesis heterocyclic molecules. Many efforts have been made to balance relationship between structure, reactivity and selectivity, including design new electrophilic halogenation reagents utilization activating strategies. However, discovering universal or strategies remains challenging due case-by-case practice different substrates cyclization models. Here we report an intramolecular chaperone-assisted dual-anchoring activation (ICDA) model halocyclization, taking advantage non-covalent orientation as driving force. This protocol allows a practical, catalyst-free rapid approach access seven types small-sized, medium-sized, large-sized units realize polyene-like domino halocyclizations, exemplified by nearly 90 examples, risk-reducing flow gram-scale synthesis. DFT studies verify crucial role ICDA in affording suitable preorganization transition state stabilization X

Language: Английский

Citations

6
Water‐Tolerant Superbase Polyoxometalate [H2(Nb6O19)]6− for Homogeneous Catalysis DOI
Soichi Kikkawa,

Yu Fujiki,

Vorakit Chudatemiya

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(17)

Published: Feb. 23, 2024

Here, doubly protonated Lindqvist-type niobium oxide cluster [H

Language: Английский

Citations

5
Scaffold‐Oriented Asymmetric Catalysis: Conformational Modulation of Transition State Multivalency during a Catalyst‐Controlled Assembly of a Pharmaceutically Relevant Atropisomer DOI
Nicolò Tampellini, Brandon Q. Mercado, Scott J. Miller

et al.

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(30)

Published: March 20, 2024

A new class of superbasic, bifunctional peptidyl guanidine catalysts is presented, which enables the organocatalytic, atroposelective synthesis axially chiral quinazolinediones. Computational modeling unveiled conformational modulation catalyst by a novel phenyl urea N-cap, that preorganizes structure into active, folded state. previously unanticipated noncovalent interaction involving difluoroacetamide acting as hybrid mono- or bidentate hydrogen bond donor emerged decisive control element inducing atroposelectivity. These discoveries spurred from scaffold-oriented project inspired fascinating investigational BTK inhibitor featuring two stable axes and relies on mechanistic framework was foreign to extant lexicon asymmetric catalysis.

Language: Английский

Citations

5
Strong Bases and beyond: The Prominent Contribution of Neutral Push–Pull Organic Molecules towards Superbases in the Gas Phase DOI Open Access
Ewa D. Raczyńska, J. Gál, Pierre‐Charles Maria

et al.

International Journal of Molecular Sciences, Journal Year: 2024, Volume and Issue: 25(11), P. 5591 - 5591

Published: May 21, 2024

In this review, the principles of gas-phase proton basicity measurements and theoretical calculations are recalled as a reminder how PA/GB scale, based on Brønsted–Lowry theory, was constructed in (PA—proton affinity and/or GB—gas-phase enthalpy Gibbs energy respectively). The origins exceptionally strong some organic nitrogen bases containing N-sp3 (amines), N-sp2 (imines, amidines, guanidines, polyguanides, phosphazenes), N-sp (nitriles) rationalized. particular, role push–pull development superbasicity region is emphasized. Some reasons for difficulties poly-functional highlighted. Various structural phenomena being relation with acid–base equilibria that should be considered quantum-chemical parameters discussed. preparation methods site protonation briefly reviewed. Finally, recent trends research neutral superbases, leaning toward catalytic other remarkable applications, underlined.

Language: Английский

Citations

5
Unique Superbase TBD (1,5,7-Triazabicyclo[4.4.0]dec-5-ene): From Catalytic Activity and One-Pot Synthesis to Broader Application in Industrial Chemistry DOI
Elke Fritz‐Langhals

Organic Process Research & Development, Journal Year: 2022, Volume and Issue: 26(11), P. 3015 - 3023

Published: Oct. 21, 2022

TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene) is an organic superbase with unique catalytic effects due to its bifunctionality. It already successfully used as a versatile catalyst, e.g., for transesterification, amidation, Michael addition, and aldol reactions, in technical silicone chemistry even enantioselective transformations. Currently, main applications are innovative polymer (vitrimers, nonisocyanate polyurethanes, polyureas). Restrictions of broader application processes limited market availability the complicated handling crystalline delivery form now overcome by simple one-pot synthesis TBD, which generates easy-to-make, ready-to-apply liquid formulation.

Language: Английский

Citations

19
Organosuperbase-Catalyzed 1,1-Diboration of Alkynes DOI
Son H. Doan,

Nhan Nu Hong Ton,

Binh Khanh

et al.

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(19), P. 12409 - 12418

Published: Sept. 28, 2022

1,1-Diboryl alkenes are versatile building blocks in organic synthesis and medicinal chemistry. However, there have been only a small number of established methods to prepare this class compounds, most them used transition-metal catalysts, which undesirable the preparation biologically relevant compounds. Herein, we report an unprecedented application P1–tBu phosphazene as superbasic organocatalyst promote 1,1-diboration reactions unactivated aromatic electron-deficient terminal alkynes. The dual Brønsted Lewis basicity enables activation reaction substrates allows for high regio- stereoselectivity be obtained. A combination thorough experimental computational studies suggests interesting mechanistic insights these phosphazene-catalyzed diboration reactions, also discussed detail.

Language: Английский

Citations

17