Theory-Guided Design of Brønsted Acid-Assisted Phosphine Catalysis: Synthesis of Dihydropyrones from Aldehydes and Allenoates.
Theory-Guided Design of Brønsted Acid-Assisted Phosphine Catalysis: Synthesis of Dihydropyrones from Aldehydes and Allenoates.
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DOI：
10.1016/j.tet.2008.04.075
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发表时间：
2008-07-14
期刊：
影响因子：
2.1
通讯作者：
Kwon, Ohyun
中科院分区：
文献类型：
--
作者：
Creech, Gardner S.;Zhu, Xue-Feng;Foncivic, Branden;Dudding, Travis;Kwon, Ohyun
膦催化的2，3-丁二烯酸酯与醛的加成反应已扩展到二取代二氢-2-吡喃的形成。两性离子β-二烯醇膦盐中间体的平衡向S-顺式中间体的必要移动是通过使用Brnsted酸添加剂实现的，该添加剂破坏了S-反式中间体中的良好库仑相互作用。通过一系列密度泛函理论计算，分析了在S-顺-β-二烯醇膦盐形成过程中Brnsted酸添加剂与膦的协同作用的详细性质。与以前报道的醛与烯丙酸酯的环化反应不同，三烷基膦是最好的催化剂，在本研究中，三苯基膦也首次被发现是合成二氢吡喃的合适催化剂。这种方法提供了从简单、稳定的起始原料一步合成功能化二氢吡喃的路线。此外，还揭示了膦催化烯丙烯环合反应的新途径，其中二氢吡喃的形成是这一领域中首次出现双重活化的例子。
The phosphine-catalyzed addition of 2,3-butadienoates to aldehydes has been extended to the formation of disubstituted dihydro-2-pyrones. The requisite shift in equilibrium of the intermediate zwitterionic β-phosphonium dienolates toward the s-cis intermediate was accomplished through the use of a Brønsted acid additive, which disrupts the favorable Coulombic interaction present in the s-trans intermediate. The detailed nature of the synergistic interactions involving the Brønsted acid additives and phosphine involved in the formation of s-cis β-phosphonium dienolates was analyzed through a series of DFT calculations. Unlike previously reported annulations of aldehydes with allenoates, where trialkylphosphines are optimal catalysts, in this study triphenylphosphine was also found for the first time to be a suitable catalyst for the synthesis of dihydropyrones. This method provides a one-step route toward functionalized dihydropyrones from simple, stable starting materials. In addition, new reaction pathways of phosphine-catalyzed allene annulations are unveiled, with the formation of dihydropyrones being the first example of dual activation in this sphere.
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影响因子：
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