Selectivity in Organic Synthesis under Microwave Irradiation
Selectivity in Organic Synthesis under Microwave Irradiation
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DOI：
10.1002/chin.200446264
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发表时间：
2004-06
期刊：
影响因子：
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通讯作者：
A. Hoz;Á. Díaz‐Ortiz;Andrés Moreno
中科院分区：
文献类型：
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作者：
A. Hoz;Á. Díaz‐Ortiz;Andrés Moreno
微波辅助有机合成以在许多反应中产生的壮观的加速而闻名，这是由于经典加热无法再现的加热速率。因此，可以实现更高的产率、更温和的反应条件和更短的反应时间，并且可以改进许多方法。此外，通过常规加热不能发生的反应通常可以在微波作用下进行。这种效应在制备半衰期短的同位素标记药物（11 C，t1/2 = 20分钟）时尤其重要。; 122 I，t1/2 = 3.6 min，18 F，t1/2 = 100 min）和高通量化学（组合化学和平行合成）。微波辐射的另一个非常重要的应用涉及相对于常规加热的选择性（化学选择性、区域选择性和立体选择性）的改变。选择性是有机合成中的一个重要目标，通常通过选择适当的反应条件、溶剂、温度、时间或使用动力学与热力学控制、保护和活化以及选择性催化剂来实现。通过简单地选择适当的加热模式（常规与微波）来控制选择性的能力是非常有吸引力的主张。然而，微波辐射的影响仍然需要合理化，以预测辐射对给定反应的选择性的影响。
Microwave Assisted Organic Synthesis is known for the spectacular accelerations produced in many reactions as a consequence of heating rates that cannot be reproduced by classical heating. As a result, higher yields, milder reaction conditions and shorter reaction times can be achieved and many processes can be improved. Furthermore, reactions that do not occur by conventional heating can often be carried out under the action of microwaves. This effect is particularly important in the preparation of isotopically labeled drugs with short half- lives ( 11 C, t1/2 = 20 min.; 122 I, t1/2 = 3.6 min. and 18 F, t1/2 = 100 min.) and high throughput chemistry (combinatorial chemistry and parallel synthesis). Another very important application of microwave irradiation involves the modification of the selectivity (chemo-, regio- and stereoselectivity) in relation to conventional heating. Selectivity is a crucial objective in organic synthesis and is usually achieved by selecting the appropriate reaction conditions, solvent, temperature, time or using kinetic vs. thermodynamic control, protection and activation and selective catalysts. The ability to control the selectivity by simply choosing the appropriate mode of heating (conventional vs. microwaves) is very attractive proposition. However, the effect of microwave irradiation still needs to be rationalized in order to predict the effect of the radiation on the selectivity of a given reaction.