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Published on: September 8, 2013
Observación de la transferencia directa de grupos de sulfenio y selenium de los iones de tiiranio y seleniranio a los
Scott E Denmark1, William R Collins, Matthew D Cullen
1Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA. sdenmark@illinois.edu
Journal of the American Chemical Society
|February 21, 2009
Resumen
Los iones de sulfenio y selenio se transfieren estereospecíficamente de los anillos de tres miembros a los alquenos. Las transferencias de selenio fueron instantáneas, mientras que las transferencias de azufre variaron, lo que indica diferentes estabilidades de estos iones de azufre y selenio.
Área de la Ciencia:
- Química del organosulfuro Química del organosulfuro
- Química del organoselenio Química del organoselenio
- Mecanismos de reacción Mecanismos de reacción
Sus antecedentes:
- Los iones de sulfenio y selenium son intermediarios reactivos.
- Las especies de anillos de tres miembros, conocidas como iones -iranio, son precursores.
- Comprender sus reacciones de transferencia es clave para las aplicaciones sintéticas.
Objetivo del estudio:
- Para investigar la transferencia estereospecífica de iones de sulfenio y selenium.
- Para comparar la reactividad y estabilidad de los iones de tiiranio y seleniranio.
- Explorar la influencia de los sustituyentes en la facilidad de transferencia y la estabilidad iónica.
Principales métodos:
- Generación de hexafluoroantimonatos de tiiranio y seleniranio utilizando hexafluoroantimonato de plata.
- Caracterización de los iones generados mediante espectroscopia de RMN (1H, 13C, 77Se).
- Estudio de las reacciones de transferencia iónica con alquenos no activados a diferentes temperaturas.
- Mediciones de equilibrio para determinar las estabilidades relativas de los iones seleniranio.
Principales resultados:
- Los iones de tiiranio mostraron una facilidad de transferencia variable; el S-feniltiiranio se transfirió lentamente, mientras que el S-metiltiiranio no se transfirió.
- Los iones de seleniranio (Se-fenilo y Se-butilo) transfirieron la fracción de selenienio instantáneamente a bajas temperaturas (-70 °C).
- Se estableció el orden de estabilidad relativa para los iones 1-fenilseleniranio: cis-tetrametileno < trans-2,3-dipropilo ≈ trans-2,3-diisopropilo < cis-hexametileno.
Conclusiones:
- Los iones de sulfenio y selenium exhiben comportamientos y estabilidades de transferencia distintos.
- Los iones de seleniranio son generalmente más reactivos y transfieren fácilmente la fracción de selenio en comparación con los iones de tiiranio.
- El estudio proporciona información sobre los factores que rigen la estabilidad y la reactividad de estos importantes intermediarios de azufre y selenio.
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