Video Experimental Relacionado

Updated: Oct 13, 2025

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Published on: March 20, 2014

Un mecanismo biomimético de acoplamiento cruzado S_H2 para la formación cuaternaria de sp³-carbono

Wei Liu¹, Marissa N Lavagnino¹, Colin A Gould¹

¹Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA.

Science (New York, N.Y.)

|November 11, 2021

Resumen

Este estudio introduce una nueva plataforma de acoplamiento cruzado biomimético utilizando sustitución homolítica bimolecular (S_H2) para crear centros cuaternarios de carbono sp³ desafiantes. El método emplea porfirina de hierro y fotocatálisis para la formación eficiente de enlaces sintéticos CC.

Área de la Ciencia:

Química orgánica
La Química Radical
Síntesis biomimética

Sus antecedentes:

La sustitución homolítica bimolecular (S_H2) es un mecanismo clave de cáscara abierta en la alquilación bioquímica.
El colector S_H2 ha sido infrautilizado en las estrategias de formación de enlaces CC sintéticos.
La construcción de centros cuaternarios de sp3 carbono sigue siendo un desafío significativo en la síntesis orgánica.

Objetivo del estudio:

Desarrollar una plataforma sintética que aproveche el mecanismo S_H2 para la formación de enlaces CC.
Permitir la construcción de centros cuaternarios de carbono sp3 mediante un enfoque biomimético.
Para utilizar la porfirina de hierro y la fotocatálisis para el acoplamiento heteroselectivo radical-radical.

Principales métodos:

Se utilizó la catálisis de la porfirina de hierro para diferenciar las funciones S_H2 de los carbonos primarios y terciarios.
Se utiliza la fotocatálisis para generar radicales alquilo primarios y terciarios simultáneamente.
Las vías mecanicistas investigadas, incluida la intermediación de las especies de alquiloFe (III).

Principales resultados:

Estableció una plataforma de acoplamiento cruzado biomimético.
Centros de carbono cuaternarios equipados con éxito, abordando un desafío sintético.
Confirmó la trayectoria de desplazamiento S_H2 en el paso clave de formación de enlaces.

Conclusiones:

El mecanismo S_H2 puede aplicarse efectivamente a la formación de enlaces CC sintéticos.
Este enfoque proporciona una nueva ruta para construir moléculas complejas con centros de carbono cuaternarios.
La combinación de porfirina de hierro y fotocatálisis ofrece una herramienta versátil para la química radical.

Más Videos Relacionados

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides

Published on: May 26, 2019

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Published on: February 7, 2019

Videos de Conceptos Relacionados

Hybridization of Atomic Orbitals II

Hybridization of Atomic Orbitals II

sp3d and sp3d 2 Hybridization

Hybridization of Atomic Orbitals I

Hybridization of Atomic Orbitals I

The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...

Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)

Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)

Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...

SN1 Reaction: Mechanism

S_N1 Reaction: Mechanism

Kinetic studies of ionization of a tertiary halide in a protic solvent suggest that only the substrate participates in the rate-determining step (slow step). The nucleophile is involved only after the slowest step. The SN1 reaction takes place in a multiple-step mechanism.
Firstly, the haloalkane ionizes to generate a carbocation intermediate and a halide ion. This heterolytic cleavage is highly endothermic with large activation energy. The ionization of the substrate, facilitated by a...

Carbocations

Carbocations

Carbocations are one of the reaction intermediates formed during several nucleophilic substitutions or elimination reactions. A carbocation is an electron-deficient species with the central carbon atom having six electrons and three bonded atoms. The central carbon in a carbocation is sp2 hybridized with trigonal planar geometry. It has an empty p orbital perpendicular to the plane of the structure that can accept electrons. Thus, carbocations act as strong electrophiles and may react with any...