Aravind A, George Sanil, Kumar Santhosh
Chemical Biology Laboratory, Division of Molecular Medicine and Disease Biology, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, 695014, India.
Chem Cent J. 2012 Apr 11;6(1):30. doi: 10.1186/1752-153X-6-30.
Morita Baylis Hillman (MBH) reaction is used to introduce carbon-carbon or carbon-heteroatom bond in a molecule. The major drawback of this reaction is the relatively low product yield and long reaction time. Though notable changes have been made to improve the reaction rate and yield of MBH adduct by various groups, a reliable synthetic procedure under ambient temperature in presence moisture and air is remain unsolved. Continuing the effort to improve the rate and yield, we report here an eco-friendly and cost-effective method to generate MBH adducts. Non-volatile polyethylene glycol-200 is used as reusable solvents and the reaction was carried out under the influence of microwave energy.
Microwave irradiation have a remarkable influence on PEG suspended 4-Diazabicyclo [2.2.2] octane (DABCO) catalysed MBH reaction between aldehydes and ethyl acrylate. Molecular weight of the PEG is found to have a significant influence on the reaction yield. PEG-200 was the most efficient solvent and in combination with DABCO, the medium can be recycled upto three more runs. This reaction condition is successfully applied to obtain MBH adduct of five different aldehydes in very short time with excellent yield and the required catalyst concentration was very low compared to standard MBH reaction. Since the MBH adduct is an important reactive intermediates for many complex organic syntheses, this approach can be successfully utilised as an alternative to existing reaction conditions.
A new method was developed to improve the reaction rate and yield of MBH reaction The PEG 200-DABCO combination provides a sustainable, non-volatile, recyclable and environment friendly solvent medium to produce MBH adducts. This medium in combination with microwave energy proved to be very effective to introduce a new carbon-carbon or a carbon-heteroatom bond in a molecule.
森田-贝利斯-希尔曼（MBH）反应用于在分子中引入碳-碳键或碳-杂原子键。该反应的主要缺点是产物收率相对较低且反应时间长。尽管各个研究团队已做出显著改进以提高MBH加合物的反应速率和收率，但在常温、有水分和空气存在的条件下，可靠的合成方法仍未解决。为继续努力提高反应速率和收率，我们在此报告一种环保且经济高效的生成MBH加合物的方法。非挥发性聚乙二醇-200用作可重复使用的溶剂，反应在微波能量的影响下进行。
微波辐射对聚乙二醇悬浮的4-二氮杂双环[2.2.2]辛烷（DABCO）催化的醛与丙烯酸乙酯之间的MBH反应有显著影响。发现聚乙二醇的分子量对反应产率有重大影响。聚乙二醇-200是最有效的溶剂，与DABCO结合使用时，该介质可循环使用多达三次以上。此反应条件成功应用于在极短时间内以优异产率获得五种不同醛的MBH加合物，与标准MBH反应相比，所需催化剂浓度非常低。由于MBH加合物是许多复杂有机合成的重要反应中间体，因此该方法可成功用作现有反应条件的替代方法。
开发了一种新方法来提高MBH反应的速率和产率。聚乙二醇200-DABCO组合提供了一种可持续、非挥发性、可回收且环境友好的溶剂介质来生产MBH加合物。该介质与微波能量结合被证明在分子中引入新的碳-碳键或碳-杂原子键方面非常有效。
