Straightforward access to tetrahydropyridine and piperidine-fused fluorolactones from pyridines and bis(trimethylsilyl)ketene acetals
作者:Henri Rudler、Andrée Parlier、Louis Hamon、Patrick Herson、Patrick Chaquin、Jean-Claude Daran
DOI:10.1016/j.tet.2009.02.086
日期:2009.7
formation of dihydropyridine-substituted carboxylic acids. These in turn reacted with selectfluor as the source of electrophilic fluorine. Whereas a discrimination of the double bonds devoid of fluorine and those bearing fluorine was observed in the case of electrophiles such as iodine, bromine and peracids, no such differentiation took place in the case of selectfluor since, besides 3,5-difluorolactones
双(三甲基甲硅烷基)乙烯酮缩醛与各种吡啶的相互作用通过形成二氢吡啶取代的羧酸而直接,一般,非对映选择性地接近氟代内酯。这些继而与作为亲电子氟源的selectfluor反应。在亲电子试剂如碘,溴和过酸的情况下,观察到没有氟的双键和带有氟的双键的区别,而在selectfluor的情况下则没有这种区别,因为除了3,5-二氟内酯外,还会形成的宝石-二氟内酯也发生了。此外,在四氢吡啶取代的羧酸的内酯化过程中形成的两个立体异构的氟内酯,是由(三甲基甲硅烷基)酮缩醛与先前的内酯相互作用而获得的,可以归因于构象修饰。在所检查的所有情况下,均观察到亲电子试剂和羧酸酯的反式,双轴加成。这些反应的立体化学结果均通过NMR光谱和X射线晶体学评估。