Functionalisation reactions of 2,5-diphenyl-1,3,4-oxadiazoles bearing a terminal ethynyl or butadiynyl substituent: X-ray crystal structures of the products
作者:David Kreher、Andrei S. Batsanov、Changsheng Wang、Martin R. Bryce
DOI:10.1039/b315694j
日期:——
whereas other attempted Wittig and Horner-Wadsworth-Emmons reactions led to the unexpected loss of the aldehyde group from compounds 5 and 6 to give 1 and 2, respectively. The X-ray crystal structures of compounds, 3, 4, 5 and 11 are reported: the pi-systems of all four molecules adopt predominantly planar conformations. A comparison of bond lengths in the structures of 5 and 11 reveals extended pi-conjugation
2-(4-叔丁基苯基)-5-(4-乙炔基苯基)-1,3,4-恶二唑1和丁二炔类似物2在碘化锌存在下与原甲酸三乙酯反应生成缩醛衍生物3和4将其用Amberlyst-15在丙酮-水中水解,以高收率得到炔基醛衍生物5和6。4,5-双(甲氧基羰基)-2-三丁基phosph-1,3-二硫代四氟硼酸盐7与5(nBuLi,THF)的反应得到Wittig产物2-(3- [4- [5-(4-tert) -丁基苯基)-1,3,4-恶二唑-2-基]苯基]丙-2-炔基)-1,3-二硫醇-4,5-二甲基二羧酸酯11(33%收率),而其他尝试了Wittig和Horner- Wadsworth-Emmons反应导致醛基意外地从化合物5和6丢失,分别得到1和2。报告了化合物3、4、5和11的X射线晶体结构:所有四个分子的pi系统主要采用平面构象。5和11结构中键长的比较表明,后者的pi共轭扩展。