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Reacciones de cicloadición oxofosfonio-alquina: Formación reversible de 1,2-oxafosfetos y heterociclos de fósforo de
Pawel Löwe1, Milica Feldt2, Marius A Wünsche1
1Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, 48149 Münster, Germany.
Journal of the American Chemical Society
|May 5, 2020
Resumen
Los iones de oxofosfonio reaccionan con los alquinos a través de la cicloadición [2 + 2], formando nuevos iones de 1,2-oxafosfeto. Estos intermedios se pueden transformar en valiosos heterociclos de fósforo de seis miembros, expandiendo las posibilidades sintéticas.
Área de la Ciencia:
- Química orgánica
- Química de los organofosforos
- Química del grupo principal
Sus antecedentes:
- La reacción de metástasis que involucra alquinas y compuestos carbonílicos es una piedra angular de la síntesis orgánica.
- La reactividad de los compuestos R2EO del grupo principal isoelectrónico con los alquinos sigue siendo en gran medida inexplorada.
- Los iones de oxofosfonio sirven como congéneres de fósforo para los compuestos carbonílicos.
Objetivo del estudio:
- Investigar las reacciones de cicloadición entre los iones de oxofosfonio y las alquinas.
- Explorar la utilidad sintética de los heterociclos resultantes que contienen fósforo.
- Para aclarar los factores electrónicos que rigen la transferencia de átomos de oxígeno en estos sistemas.
Principales métodos:
- [2 + 2] reacciones de cicloadición entre iones de oxofosfonio y varios alquinos.
- Aislamiento y caracterización estructural de los iones 1,2-oxafosfeto.
- Apertura térmica del anillo de los heterociclos para formar intermedios heterodienos.
- Las reacciones de Hetero Diels-Alder para la síntesis de heterociclos de fósforo de seis miembros.
- Cálculos químicos cuánticos para estudiar los mecanismos de reacción y los efectos de los sustituyentes.
Principales resultados:
- La adición exitosa [2 + 2] de iones de oxofosfonio con alquinos para formar iones 1,2-oxafosfeto.
- Aislamiento y caracterización estructural completa de estos nuevos heterociclos de fósforo y oxígeno tensados.
- Demostración de la apertura del anillo térmico a los intermedios heterodienos.
- Las reacciones hetero Diels-Alder posteriores permitieron la síntesis de diversos heterociclos de fósforo de seis miembros.
- Los cálculos químicos cuánticos proporcionaron información sobre los efectos de los sustituyentes en las energías de transferencia de átomos de oxígeno.
Conclusiones:
- Los iones de oxofosfonio son socios reactivos para las alquinas en [2 + 2] cicloadiciones, dando iones únicos de 1,2-oxafosfeto.
- Estos heterociclos de fósforo sirven como precursores versátiles para construir sistemas de anillos que contienen fósforo más complejos.
- El estudio amplía la caja de herramientas sintéticas para la química de organofosforos y las transformaciones de elementos del grupo principal.
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