Catalitic enantioselective alkylative dearomatization-annulation: síntesis total y asignación de la configuración
Ji Qi1, Aaron B Beeler, Qiang Zhang
1Department of Chemistry and Center for Chemical Methodology and Library Development, Boston University, Boston, Massachusetts 02215, USA.
Journal of the American Chemical Society
|September 14, 2010
Resumen
La síntesis total de hiperibona K se logró a través de una reacción de dearomatización-anulación enantioselectiva. Este estudio también exploró el mecanismo de un catalizador de transferencia de fase quiral.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Química sintética de la química sintética.
- La catálisis es la catálisis.
Sus antecedentes:
- Los acilphloroglucinols poliprenylated son una clase de productos naturales con actividades biológicas potenciales.
- Hyperibone K es un compuesto específico dentro de esta clase que presenta un complejo desafío sintético.
Objetivo del estudio:
- Para lograr la primera síntesis total asimétrica de hiperibona K.
- Para investigar el mecanismo de un catalizador de transferencia de fase quiral utilizado en la síntesis.
Principales métodos:
- Reacción de dearomatización-anulación alquilativa y enantioselectiva.
- Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN).
- Estudios computacionales (por ejemplo, cálculos de DFT).
Principales resultados:
- El éxito de la síntesis total asimétrica de hiperibona K.
- Elucidación del modo de acción catalítica para el catalizador quiral de transferencia de fase.
Conclusiones:
- La estrategia sintética desarrollada proporciona acceso a la hiperibona K.
- Comprender el mecanismo del catalizador puede ayudar en el diseño de futuros sistemas catalíticos.
Más Videos Relacionados
Videos de Conceptos Relacionados
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
01:14Alkylation of β-Diester Enolates: Malonic Ester Synthesis
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
01:07Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis
Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide base that abstracts the acidic proton of the β-keto esters. The step results in an enolate ion which is doubly stabilized. The enolate then reacts with an alkyl halide via the SN2 process to produce an alkylated ester intermediate with a new C–C bond. The hydrolysis of the intermediate, followed by acidification, results in an alkylated β-keto acid.
01:10α-Alkylation of Ketones via Enolate Ions
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the strong interaction...
![[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12422.jpg&w=3840&q=75)
01:21[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...