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Reacción en cascada selectiva [2 + 2]-cicloadición y desaromatización catalizada por el ácido de Lewis de alquinas

Liang Shen¹, Kai Zhao^2,1, Kazuki Doitomi³

¹Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore , 637371.

Journal of the American Chemical Society

|September 8, 2017

Resumen

Este estudio introduce un método eficiente catalizado por In{tfacac) 3-TMSBr para la síntesis de ciclobutenos y decalinas. El sistema de ácido de Lewis combinado permite reacciones en cascada selectivas [2+2] y desaromatizantes con alta estereoselectividad.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

Los ácidos de Lewis combinados pueden exhibir propiedades catalíticas únicas no alcanzables por componentes individuales.
La síntesis eficiente de ciclobutenos y decalinas es crucial debido a su presencia en productos naturales y su utilidad sintética.

Objetivo del estudio:

Desarrollar un método eficiente para la síntesis de ciclobutenos y esqueletos de decalina densamente funcionalizados.
Explorar las capacidades catalíticas de un sistema de ácido de Lewis combinado para la cicloadición y las reacciones en cascada.

Principales métodos:

Utilizó indio ((III) trifluoroacetilacetonato [In ((tfacac) 3) y bromuro de trimetilsililo (TMSBr) como catalizador combinado de ácido de Lewis.
Se realizó una adición selectiva [2+2]-ciclo de alquinas arílicas con acrilatos.
Investigó las reacciones en cascada de desaromatización.
Se han realizado estudios mecanicistas y computacionales.

Principales resultados:

Se logró una síntesis eficiente de ciclobutenos y esqueletos de decalina densamente funcionalizados con alta quimioselectividad y estereoselectividad.
Se ha demostrado la conversión de ciclobutanos en ciclobutanos y en 1,4- y 1,5-dicetonas valiosas.
Mecanismos de reacción plausibles propuestos tanto para las vías de cicloadición como para las de cascada.

Conclusiones:

El sistema combinado de ácido de Lewis In(tfacac) 3-TMSBr cataliza efectivamente las reacciones en cascada selectivas de adición de ciclo [2+2] y desaromatización.
La metodología desarrollada permite el acceso a derivados sintéticos importantes del ciclobuteno y la decalina.
Los estudios computacionales apoyan los mecanismos propuestos y destacan el efecto sinérgico del ácido de Lewis combinado.

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