Preparation of chiral bipyridine bis-N-oxides by oxidative dimerization of chiral pyridine N-oxides
作者:Scott E. Denmark、Yu Fan
DOI:10.1016/j.tetasy.2005.12.039
日期:2006.2
The direct preparation of chiral 2,2′-bipyridine bis-N-oxides has been developed. The method involves two stages, first, the deprotonation of substituted chiral pyridine N-oxides and second, the oxidative dimerization of the resulting 2-lithiopyridine N-oxides. Optimization of the reaction conditions led to the selection of LiTMP in THF for the deprotonation and molecular iodine as the oxidant. The
已经开发了直接制备手性2,2'-联吡啶双-N-氧化物的方法。该方法包括两个阶段,第一,去质子化取代的手吡啶Ñ -oxides和第二,所得到的2-lithiopyridine的氧化二聚Ñ -oxides。反应条件的优化导致选择了THF中的LiTMP用于去质子反应,并选择了分子碘作为氧化剂。相应的2-碘吡啶N-氧化物总是作为副产物形成。制备了一系列11个手性吡啶N-氧化物,它们在C(2)和C(5)位置带有取代基。这些单氮的氧化二聚氧化物的产率为33–77%。在所有情况下,二聚化对于形成手性轴的P-构型是高度非对映选择性的。