Microwave Heating Outperforms Conventional Heating for a Thermal Reaction that Produces a Thermally Labile Product: Observations Consistent with Selective Microwave Heating
Microwave Heating Outperforms Conventional Heating for a Thermal Reaction that Produces a Thermally Labile Product: Observations Consistent with Selective Microwave Heating
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DOI：
10.1002/asia.201900625
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发表时间：
2019-08-01
影响因子：
4.1
通讯作者：
Dudley, Gregory B.
中科院分区：
文献类型：
--
作者：
Duangkamol, Chuthamat;Batsomboon, Paratchata;Dudley, Gregory B.
微波（MW）加热比传统（CONV）加热更有效地促进了高温氧化环异构化反应，这是以前报道的天然产物illuminine全合成的关键步骤。设想的热反应途径是逆电按需脱氢- diels - alder反应与原位氧化生成取代异喹啉，其本身对反应条件不稳定。在测量体温为200℃时，观察到的反应产率比在180℃或220℃时高；比早或晚的时间点早24小时；当反应溶液用MW能量加热而不是用金属热块进行CONV加热时。假设极性溶质聚集体的选择性微波加热可以解释这些观察结果。
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 degrees C than at 180 degrees C or 220 degrees 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.