Investigation of the Origins of Regiochemical Control in [4+2] Cycloadditions of 2-Pyrones and Alkynylboronates
作者:Joseph Harrity、James Kirkham、Andrew Leach、Eleanor Row
DOI:10.1055/s-0031-1291142
日期:2012.7
Abstract The [4+2] cycloaddition of 2-pyrones with substituted alkynylboronates has been studied. In general, the highest yielding cycloadditions were obtained in reactions that employed a trimethylsilyl-substituted alkynylboronate. The highest regioselectivities were obtained using the corresponding phenyl-substituted alkyne, which provided a single regioisomer irrespective of the 2-pyrone used. Mechanistic
摘要 研究了2-吡喃酮与取代的炔基硼酸酯的[4 + 2]环加成反应。通常,在使用三甲基甲硅烷基取代的炔基硼酸酯的反应中获得最高产率的环加成。使用相应的苯基取代的炔烃可得到最高的区域选择性,该炔烃可提供单一的区域异构体,而与所用的2-吡喃酮无关。机理研究表明,观察到的高区域选择性是由于两性离子过渡态的稳定所致。 研究了2-吡喃酮与取代的炔基硼酸酯的[4 + 2]环加成反应。通常,在使用三甲基甲硅烷基取代的炔基硼酸酯的反应中获得最高产率的环加成。使用相应的苯基取代的炔烃可得到最高的区域选择性,该炔烃可提供单一的区域异构体,而与所用的2-吡喃酮无关。机理研究表明,观察到的高区域选择性是由于两性离子过渡态的稳定所致。