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Sulfonilación regioselectiva catalítica de alcoholes alfaquelables: alcance y conocimiento mecanicista

Michael J Martinelli¹, Rajappa Vaidyanathan, Joseph M Pawlak

¹Chemical Process R&D, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana 46285-4813, USA. mjm@lilly.com

Journal of the American Chemical Society

|April 4, 2002

Resumen

Este estudio presenta un método sencillo para la tosilación regioselectiva de alcohol utilizando óxido de dibutiltina. El protocolo permite la monotosilación rápida y exclusiva de alcoholes alfa-heterosubstituidos, con velocidades de reacción influenciadas por la basicidad de las aminas.

Área de la Ciencia:

Química orgánica es la química orgánica.
Metodología sintética de la metodología sintética.
Química organometálica Química orgánica de los metales.

Sus antecedentes:

La sulfonilación de los alcoholes es una transformación fundamental en la síntesis orgánica.
La regioselectividad es a menudo un desafío en la funcionalización de moléculas polifuncionales.
El desarrollo de métodos eficientes y selectivos para la derivación de alcohol sigue siendo un área activa de investigación.

Objetivo del estudio:

Desarrollar un protocolo conveniente y regioselectivo para la monotosilación de alcoholes alfa-heterosubstituidos.
Investigar la influencia de los parámetros de reacción, como la basicidad de aminas, en la reacción de tosilación.
Para aclarar el mecanismo del sistema catalítico propuesto.

Principales métodos:

Reacción de los alcoholes alfa-heterosubstituidos con el cloruro de p-toluenesulfonilo (p-TsCl) y la trietilamina (Et(3) N).
La catálisis utilizando 2 mol % de óxido de dibutiltina (Bu(2) SnO).
Estudios cinéticos y espectroscopia de RMN (119) Sn para sondear el mecanismo de reacción.

Principales resultados:

El protocolo proporciona una monotosilación rápida, regioselectiva y exclusiva de los alcoholes alfa-quelables.
Se encontró que las tasas de reacción se correlacionan con la pK (a) de la base amina utilizada.
Se propuso un ciclo catalítico plausible que involucra óxido de dibutiltina basado en estudios mecanicistas.

Conclusiones:

Se ha establecido un método novedoso y eficiente para la tosilación regioselectiva de alcohol.
El sistema catalítico ofrece un enfoque práctico para la funcionalización selectiva de los alcoholes.
Los conocimientos mecanicistas proporcionan una comprensión más profunda de las reacciones orgánicas mediadas por el estaño.

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