Enantioselective Aziridination of Unactivated Terminal Alkenes Using a Planar Chiral Rh(III) Indenyl Catalyst

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(2), P. 1447 - 1454

Published: Jan. 3, 2024

Chiral aziridines are important structural motifs found in natural products and various target molecules. They serve as versatile building blocks for the synthesis of chiral amines. While advances catalyst design have enabled robust methods enantioselective aziridination activated olefins, simple abundant alkyl-substituted olefins pose a significant challenge. In this work, we introduce novel approach utilizing planar rhodium indenyl to facilitate unactivated alkenes. This transformation exhibits remarkable degree functional group tolerance displays excellent chemoselectivity favoring alkenes over their counterparts, delivering wide range enantioenriched high-value aziridines. Computational studies unveil stepwise mechanism which alkene migratory insertion plays central role. process results formation strained four-membered metallacycle serves both enantio- rate-determining steps overall reaction.

Language: Английский

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Origin of the α‐Effect in S_N2 Reactions

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(38), P. 20840 - 20848

Published: June 4, 2021

The α-effect is a term used to explain the dramatically enhanced reactivity of α-nucleophiles (R-Y-X:

Language: Английский

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An easy-to-perform evaluation of steric properties of Lewis acids

Chemical Science, Journal Year: 2023, Volume and Issue: 14(9), P. 2275 - 2288

Published: Jan. 1, 2023

An easy-to-perform approach to assess and quantify steric properties of Lewis acids is reported. The novel LAB-Rep model (Lewis acid/base repulsion model) introduced, which judges in pairs.

Language: Английский

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Catalytic Enantioselective Intramolecular Oxa-Michael Reaction to α,β-Unsaturated Esters and Amides

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(23), P. 12771 - 12782

Published: May 30, 2023

A bifunctional iminophosphorane (BIMP)-catalyzed, enantioselective intramolecular oxa-Michael reaction of alcohols to tethered, low electrophilicity Michael acceptors is described. Improved reactivity over previous reports (1 day vs 7 days), excellent yields (up 99%), and enantiomeric ratios 99.5:0.5 er) are demonstrated. The broad scope, enabled by catalyst modularity tunability, includes substituted tetrahydrofurans (THFs) tetrahydropyrans (THPs), oxaspirocycles, sugar natural product derivatives, dihydro-(iso)-benzofurans, iso-chromans. state-of-the-art computational study revealed that the enantioselectivity originates from presence several favorable intermolecular hydrogen bonds between BIMP substrate induce stabilizing electrostatic orbital interactions. newly developed catalytic approach was carried out on multigram scale, multiple adducts were further derivatized an array useful building blocks, providing access enantioenriched biologically active molecules products.

Language: Английский

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Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

Beilstein Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: 21, P. 412 - 420

Published: Feb. 21, 2025

A new series of o -carborane-fused pyrazoles has been recently successfully synthesized. This fusion was expected to create a hybrid 3D/2D aromatic system, combining the 3D aromaticity -carborane with 2D pyrazole. However, while boron cage retains its character, pyrazole’s is lost. As result, rather than forming pyrazoles, synthesis yielded pyrazolines, which are non-aromatic. The limited overlap between π molecular orbitals (MOs) planar heterocycle and n + 1 MOs carborane prevents significant electronic delocalization two fused components. contrasts pyrazole benzene form indazole, where both rings maintain their aromaticity. Our findings demonstrate that peripheral σ-aromaticity π-aromaticity orthogonal, making true system unachievable. highly aromatic, generating negative NICS values (−25 −30 ppm). We have observed these high extend rings, leading incorrect estimations Therefore, relying solely on can be misleading, other computational indicators, along experimental or structural data, should used accurately assess

Language: Английский

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Understanding the reactivity of frustrated Lewis pairs with the help of the activation strain model–energy decomposition analysis method

Chemical Communications, Journal Year: 2022, Volume and Issue: 58(32), P. 4931 - 4940

Published: Jan. 1, 2022

This Feature article presents recent representative applications of the combination Activation Strain Model reactivity and Energy Decomposition Analysis methods to understand Frustrated Lewis Pairs (FLPs).

Language: Английский

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Origin of asynchronicity in Diels–Alder reactions

Physical Chemistry Chemical Physics, Journal Year: 2021, Volume and Issue: 23(36), P. 20095 - 20106

Published: Jan. 1, 2021

Quantum chemical activation strain analyses reveal that asynchronicity in Diels–Alder reactions reduces both destabilizing Pauli repulsion as well stabilizing orbital interactions, and occurs if the former dominates.

Language: Английский

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The 1,3‐Dipolar Cycloaddition: From Conception to Quantum Chemical Design

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

Published: July 13, 2022

The 1,3-dipolar cycloaddition (1,3-DCA) reaction, conceptualized by Rolf Huisgen in 1960, has proven immensely useful organic, material, and biological chemistry. uncatalyzed, thermal transformation is generally sluggish unselective, but the reactivity can be enhanced means of metal catalysis or introduction either predistortion electronic tuning dipolarophile. These promoted reactions go with a much higher reactivity, selectivity, yields, often at ambient temperatures. rapid orthogonal compatibility aqueous physiological conditions positions 1,3-DCA as an excellent bioorthogonal reaction. Quantum chemical calculations have been critical for providing understanding physical factors that control selectivity 1,3-DCAs. In silico derived design principles invaluable new dipolarophiles tailored reactivity. This review discusses everything from conception all way to state-of-the-art methods models used quantum novel (bioorthogonal) reagents.

Language: Английский

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Nature and strength of group-14 A–A′ bonds

Chemical Science, Journal Year: 2024, Volume and Issue: 15(5), P. 1648 - 1656

Published: Jan. 1, 2024

We have quantum chemically investigated the nature and stability of C-C Si-Si bonds in R3A-AR3 (A = C, Si; R3 H3, Me3, Me2Ph, MePh2, Ph3, t-Bu3) using density functional theory (DFT). Systematic increase steric bulk substituents R has opposite effects on bonds: former becomes weaker whereas latter stronger. Only upon going further, from Ph to bulkiest t-Bu, R3Si-SiR3 bond begins weaken. Our bonding analyses show how different behavior increasing stems interplay (Pauli) repulsive (dispersion) attractive mechanisms. Extension our other model systems shows that C-Si display is between bonds. Further size group-14 atoms Ge-Ge, Sn-Sn Pb-Pb leads a further decrease sensitivity strength with respect substituents' bulkiness. findings can be used as design principles for tuning A-A A-A' strengths.

Language: Английский

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“Hydridic Hydrogen-Bond Donors” Are Not Hydrogen-Bond Donors

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(37), P. 25701 - 25709

Published: Sept. 3, 2024

Herein, we dismiss a recent proposal by Civiš, Hobza, and co-workers to modify the IUPAC definition of hydrogen bonds in order expand scope from protonic Y-H

Language: Английский

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