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A high-temperature retro-Diels–Alder reaction is accelerated by microwave (MW) heating to rates higher than expected based on Arrhenius kinetics and the measured temperature of the reaction mixture. Observations are consistent with selective MW heating of the polar reactant relative to other, less polar components of the reaction mixture.
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Microwave Heating Outperforms Conventional Heating for a Thermal Reaction that Produces a Thermally Labile Product: Observations Consistent with Selective Microwave Heating
Abstract Microwave (MW) heating is more effective than conventional (CONV) heating for promoting a high‐temperature oxidative cycloisomerization reaction that was previously reported as a key step in a total synthesis of the natural product illudinine. The thermal reaction pathway as envisioned is an inverse electron‐demand dehydro‐Diels–Alder reaction with in situ oxidation to generate a substituted isoquinoline, which itself is unstable to the reaction conditions. Observed reaction yields were higher at a measured bulk temperature of 200 °C than at 180 °C or 220 °C; at 24 hours than at earlier or later time points; and when the reaction solution was heated using MW energy as opposed to CONV heating with a metal heat block. Selective MW heating of polar solute aggregates is postulated to explain these observations.
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- Award ID(s):
- 1665029
- PAR ID:
- 10118034
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – An Asian Journal
- Volume:
- 14
- Issue:
- 15
- ISSN:
- 1861-4728
- Format(s):
- Medium: X Size: p. 2594-2597
- Size(s):
- p. 2594-2597
- Sponsoring Org:
- National Science Foundation
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