Application of Electron-Withdrawing Coordinatively Unsaturated η<sup>6</sup>-Arene β-Diketiminato–Ruthenium Complexes in Lewis Acid Catalyzed Diels–Alder Reactions
作者:Dominique F. Schreiber、Yannick Ortin、Helge Müller-Bunz、Andrew D. Phillips
DOI:10.1021/om200566a
日期:2011.10.24
the half-sandwich chloro-substituted Ru(II) β-diketimino complexes in high yield. The synthesis of the Lewis acidic catalysts featuring a vacant coordination site at the metal center was accomplished using [Na]BArF (BArF = tetrakis[3,5-bis(trifluoromethyl)phenyl]boron). These complexes are active for the Lewis acid catalyzed Diels–Alder reaction between α,β-unsaturated aldehydes, that is, methacrolein
利用涉及3,5-(CF 3)2 C 6 H 3 NPPh 3和3,1-,1,1,5,5,5-六氟-2,4-戊二酮的高氮和电子的aza-Wittig反应获得了β-二酮消除的β。使用强碱n BuLi,Ag 2 O或TlOEt,制备了相应的β-二酮亚氨基-Li,-Ag或-T1螯合复合物。随后在原位转移金属化(茹(η 6 -C 6 H ^ 6)氯2)2或(茹(η 6 - p -cymene)氯2)2以高收率得到了半夹心的氯代氯取代的Ru(II)β-二酮亚氨基络合物。使用[Na] BArF(BArF =四[3,5-双(三氟甲基)苯基]硼)完成在金属中心具有空位配位点的路易斯酸性催化剂的合成。这些配合物对于路易斯酸催化的α,β-不饱和醛(即甲基丙烯醛,丙烯醛和二烯)即环戊二烯和2,3-二甲基-1,3-丁二烯之间的狄尔斯-阿尔德反应具有活性在温和条件下为66–98%。尽管本文描述的催化剂通常会促进甲基丙烯醛和环戊二烯之间的[4