Una cascada oxidativa inducida por desaromatización [5 + 2] que permite la síntesis de α-cedreno, α-pipitzol y sec-cedrenol

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Jason C Green¹, Thomas R R Pettus

¹Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.

Journal of the American Chemical Society

|January 4, 2011

Resumen

Los investigadores desarrollaron una nueva síntesis para compuestos de cedreno como el α-cedreno, el α-pipitzol y el sec-cedrenol. Este nuevo método utiliza la desaromatización oxidativa y una cicloadición intramolecular [5 + 2] clave, inspirada en las vías naturales de biosíntesis.

Área de la Ciencia:

Química orgánica es la química orgánica.
Síntesis de Productos Naturales.
La biosíntesis es la biosíntesis.

Sus antecedentes:

Los sesquiterpenos tricíclicos como el cedrol son productos naturales complejos.
Los métodos sintéticos existentes para estos compuestos pueden ser largos e ineficientes.
La comprensión de las vías biosintéticas puede inspirar nuevas estrategias sintéticas.

Objetivo del estudio:

Desarrollar una ruta sintética eficiente para el α-cedreno, el α-pipitzol y el sec-cedrenol.
Para utilizar una nueva desaromatización oxidativa seguida de una cicloadición intramolecular [5 + 2].
Para imitar las vías biosintéticas propuestas para esqueletos de sesquiterpenos tricíclicos.

Principales métodos:

Desaromatización oxidativa de los precursores fenólicos (curcupenoles).
Cicloadición intramolecular [5 + 2] de productos intermedios de fenoxonio con olefinas atadas.
Reacción en cascada estereoselectiva que incorpora ácido acético para formar un tercer estereocentro.
Síntesis de precursores fenólicos a partir de salicilaldehídos, lo que permite la preparación racémico o enantiomérico.

Principales resultados:

Se logró una síntesis eficiente de α-cedreno, α-pipitzol y sec-cedrenol.
La clave de la reacción de cicloadición [5 + 2] fue guiada por un estereocentro bencílico, controlando la estereoquímica inicial.
Una nueva secuencia en cascada selectivamente incorporó ácido acético, estableciendo un tercer estereocentro.
El método proporciona un enfoque distinto en comparación con las reacciones catiónicas [5 + 2] anteriores.

Conclusiones:

Se ha establecido una nueva y eficiente estrategia sintética para los sesquiterpenos tricíclicos complejos.
El método aprovecha la inspiración biosintética para las transformaciones clave.
El enfoque desarrollado ofrece un control estereoquímico preciso y amplía las posibilidades sintéticas.

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