Molecular dynamics simulation study of post‐transition state bifurcation: A case study on the ambimodal transition state of dipolar/Diels–Alder cycloaddition

Journal of Physical Organic Chemistry, Journal Year: 2024, Volume and Issue: 37(8)

Published: May 3, 2024

Abstract The potential energy surfaces for the reactions of 1,3‐butadiene with 2‐hydroxythioacrolein and 2‐aminoacrolein exhibit ambimodal transition states leading to both dipolar (4 + 3) Diels–Alder 2) cycloaddition products, thereby demonstrating a post state bifurcation feature. We have investigated dynamics these using three molecular (MD) methods: quasi‐classical trajectory, classical MD, ring‐polymer MD simulations. trajectory calculations were performed semiempirical GFN2‐xTB method element‐specific parameters optimized reproduce density‐functional theory calculations. effect water solvation was examined an implicit model, revealing significant differences in dynamic between gas‐phase solution‐phase reactions. Nuclear quantum effects found play crucial role proton‐transfer process from intermediate product case reaction.

Language: Английский

---

Vibrationally Assisted Tunneling through the Bread of a Proton Sandwich─Connections to Dynamic Matching

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 4, 2025

Proton sandwiches are unusual nonclassical carbocations characterized by a five-center, four-electron bonding array which rapidly isomerize to lower energy isomers with three-center, two-electron arrays via hydrogen migration transition states. These reactions suspected involve significant contributions from tunneling, even at relatively high temperatures, where tunneling effects usually minimal. Machine-learning-accelerated ring-polymer, quasiclassical, and classical ab initio molecular dynamics simulations were used investigate the of flavor dynamic matching that involves coupling vibrational modes reactant structure mode an imaginary frequency, how quantum mechanical affects this coupling. nonstatistical quantified analysis momentum in simulations. We show importance for reactivity without amplifies these benefits, can be leveraged generate beneficial momentum.

Language: Английский

---

Highly Diastereodivergent Green Synthesis of Cyclohexanones via Double Michael Addition of Malononitrile to Dibenzalacetone

Tetrahedron, Journal Year: 2025, Volume and Issue: unknown, P. 134637 - 134637

Published: April 1, 2025

Language: Английский

---

Hexafluoroisopropanol Solvent Effects on Enantioselectivity of Dirhodium Tetracarboxylate-Catalyzed Cyclopropanation

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: April 16, 2025

In recent years, additives that modulate both reactivity and selectivity in rhodium-catalyzed reactions of aryldiazoacetates have become increasingly prominent. 1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) has been shown to a profound effect on rhodium carbene selectivity, especially enabling cyclopropanation the presence various nucleophilic poisons. HFIP also variable influence enantioselectivity catalyzed by chiral dirhodium tetracarboxylates, this study examines fundamental properties carbene/HFIP system through experimentation, density functional theory (DFT), molecular dynamics (MD) simulations. These studies revealed C4-symmetric bowl-shaped catalysts, which previously considered be relatively rigid, experience far greater flexibility hydrogen bonding media, resulting distortion catalysts. explain why even though majority catalysts drop HFIP, some such as Rh2(TCPTAD)4, lead switch enantioselectivity, whereas others, Rh2(NTTL)4, considerably enhanced enantioselectivity.

Language: Английский

---

D₄-Symmetric Dirhodium Tetrakis(binaphthylphosphate) Catalysts for Enantioselective Functionalization of Unactivated C–H Bonds

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(28), P. 19460 - 19473

Published: July 3, 2024

Dirhodium tetrakis(2,2′-binaphthylphosphate) catalysts were successfully developed for asymmetric C–H functionalization with trichloroethyl aryldiazoacetates as the carbene precursors. The 2,2′-binaphthylphosphate (BNP) ligands modified by introduction of aryl and/or chloro functionality at 4,4′,6,6′ positions. As BNP are C2-symmetric, resulting dirhodium complexes expected to be D4-symmetric, but X-ray crystallographic and computational studies revealed this is not always case because internal T-shaped CH−π aryl–aryl interactions between ligands. optimum catalyst Rh2(S-megaBNP)4, 3,5-di(tert-butyl)phenyl substituents 4,4′ positions 6,6′ This adopts a D4-symmetric arrangement ideally suited site-selective unactivated tertiary sites high levels enantioselectivity, outperforming best tetracarboxylate reaction. standard reactions conducted loading 1 mol % lower loadings can used if desired, illustrated in cyclohexane 91% ee 0.0025 (29,400 turnover numbers). These further illustrate effectiveness donor/acceptor carbenes intermolecular expand toolbox available catalyst-controlled functionalization.

Language: Английский

---

Temperature effects on the branching dynamics in the model ambimodal (6 + 4)/(4 + 2) intramolecular cycloaddition reaction

Journal of Computational Chemistry, Journal Year: 2024, Volume and Issue: 45(32), P. 2778 - 2785

Published: Aug. 21, 2024

C

Language: Английский

---

Vibrational synchronization and its reaction pathway influence from an entropic intermediate in a dirhodium catalyzed allylic C–H activation/Cope rearrangement reaction

Physical Chemistry Chemical Physics, Journal Year: 2024, Volume and Issue: 26(15), P. 11386 - 11394

Published: Jan. 1, 2024

In the dynamically stepwise reaction pathway C–H insertion versus Cope selectivity is highly influenced by whether or not vibrational synchronization occurs in nonstatistical entropic intermediate.

Language: Английский

---

Quantum Chemical Interrogation of Reactions Promoted by Dirhodium Tetracarboxylate Catalysts─Mechanism, Selectivity, and Nonstatistical Dynamic Effects

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: 57(14), P. 1931 - 1940

Published: June 26, 2024

ConspectusRh

Language: Английский

---

Trajectory-Based Time-Resolved Mechanism for Benzene Reductive Elimination from Cyclopentadienyl Mo/W Phenyl Hydride Complexes

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(24), P. 4775 - 4786

Published: June 5, 2024

Calculated potential energy structures and landscapes are very often used to define the sequence of reaction steps in an organometallic mechanism interpret kinetic isotope effect (KIE) measurements. Underlying most this structure-to-mechanism translation is use statistical rate theories without consideration atomic/molecular motion. Here we report direct dynamics simulations for benzene reductive elimination reaction, where nonstatistical intermediates dynamic-controlled pathways were identified. Specifically, single spin state as well mixed quasiclassical trajectories gas phase explicit solvent from Mo W bridged cyclopentadienyl phenyl hydride complexes ([Me

Language: Английский

---

Molecular Dynamics of the Davies Ambimodal C–H Functionalization/Cope Rearrangement Reaction

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 19, 2024

The mechanism of the dirhodium-catalyzed combined C–H functionalization/Cope rearrangement (CH/Cope) reaction discovered by Davies group has been investigated with density functional theory (DFT) calculations and quasi-classical molecular dynamics (MD) simulations. Computations from previously showed that there is a post-transition state bifurcation leading to direct CH also CH/Cope product. While this work was in preparation, Tantillo Ess independently reported quantum mechanical studies on dirhodium-tetracarboxylate-catalyzed diazoester insertion reactions 1,3-cyclohexadiene 1,4-cyclohexadiene, respectively. cited "dynamic mismatching" explain origins low yield products some experiments; explained product selectivity perspective TS vibrational modes their synchronization occurs at entropic intermediates. We report trajectories for carbene 1-methylcyclohexene afford both products. After passing through transition involves mostly hydrogen transfer, momentum drives toward

Language: Английский

---