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Cíclicación de Prins catalizada por FeCl3 y completamente selectiva para OH: síntesis altamente estereoselectiva de

Ke Zheng¹, Xiaohua Liu, Song Qin

¹Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.

Journal of the American Chemical Society

|October 4, 2012

Resumen

Una nueva reacción de Prins catalizada por cloruro de hierro (III) permite la síntesis altamente estereoselectiva de 4-hidroxilo-tetrahidropiranos. Este método eficiente logra una excelente selectividad para una amplia gama de sustratos en condiciones suaves.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis es la catálisis.
Síntesis estereoselectiva de síntesis.

Sus antecedentes:

La ciclización de Prins es una reacción valiosa para la formación de anillos de tetrahidropirano.
Lograr una alta estereoselectividad y tolerancia al grupo funcional en las ciclizaciones de Prins sigue siendo un desafío.

Objetivo del estudio:

Desarrollar una ciclización de Prins completamente selectiva para el hidroxilo (OH).
Para sintetizar diversos 4-hidroxilo-tetrahidropiranos con un excelente control estéreo.

Principales métodos:

Una reacción enantioselectiva seguida de una ciclización de Prins catalizada por FeCl(3).
Utilizó estudios sobre el Efecto Nuclear Overhauser (NOE) y (18) etiquetado con O para investigaciones mecanicistas.
Empleó cálculos de la Teoría Funcional de Densidad (DFT) para dilucidar las vías de reacción.

Principales resultados:

Se logró la formación exclusiva de 4-hidroxilo-tetrahidropiranos.
Se obtuvieron excelentes estereoselectividades (hasta una relación diastereomérica >99:1 y una relación enantiomérica >99.5:0.5).
La reacción demostró un amplio alcance de sustrato y funcionó en condiciones suaves.

Conclusiones:

La ciclización de Prins desarrollada es altamente OH-selectiva y estereoselectiva.
Se propone un mecanismo de cicloadición [2 + 2] para explicar la selectividad OH observada.
Este método proporciona una poderosa herramienta para sintetizar complejos derivados del tetrahidropirano.

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