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Alquilación alilica catalizada por Pd de iminas sintonizables por quimioterapia y regioselectividad
Jian-Ping Chen1, Qian Peng, Bai-Lin Lei
1Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
Journal of the American Chemical Society
|August 11, 2011
Resumen
Los α-carbaniones de las iminas son nucleófilos efectivos en la alquilación alilica catalizada por el paladio. Diferentes bases y disolventes controlan la quimioselectividad y la regioselectividad, produciendo productos ramificados o lineales con alta estereoselectividad.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- La alquilación alilica catalizada por paladio es una poderosa reacción de formación de enlaces carbono-carbono.
- El uso de carbaniones derivados de imina como nucleófilos ofrece posibilidades sintéticas únicas.
Objetivo del estudio:
- Investigar la aplicación de α-carbaniones de iminas cíclicas y acíclicas en la alquilación alílica catalizada por Pd.
- Para controlar la quimioselectividad y la regioselectividad utilizando diferentes condiciones de reacción.
- Para dilucidar el mecanismo de reacción.
Principales métodos:
- Utilizó α-carbaniones de iminas como nucleófilos.
- Se empleó la catálisis del paladio para la alquilación alílica.
- Varias bases (t-BuOK, LDA) y disolventes (THF, tolueno) para ajustar la selectividad.
- Realizó cálculos de DFT para apoyar propuestas mecanicistas.
Principales resultados:
- Logró una aplicación exitosa de los α-carbaniones de imina en la alquilación alilica catalizada por Pd.
- Se ha demostrado un alto control de la quimio- y regioselectividad mediante el ajuste de los sistemas base/solvente.
- Se obtienen productos predominantemente ramificados con t-BuOK/THF y productos lineales con LDA/tolueno.
- Se han reportado elevadas selectividades regionales y diastereológicas para ambos tipos de productos.
Conclusiones:
- Los α-carbaniones de imina son nucleófilos versátiles para la alquilación alilica catalizada por Pd.
- Las condiciones de reacción influyen significativamente en la distribución y la selectividad del producto.
- Se propuso una vía mecanicista consistente con los datos experimentales y computacionales.
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