Double Bonds in Motion: Bis(oxazolinylmethyl)pyrroles and Their Metal-Induced Planarization to a New Class of Rigid Chiral C2-symmetric Complexes
作者:Clément Mazet、Lutz H. Gade
DOI:10.1002/chem.200390202
日期:2003.4.14
palladium-induced shift of two double bonds as well as the porphyrinogen/porphyrin-type oxidation of the complexes 4 a-c led to the planarization of the 2,5-bis(oxazolinylmethyl)pyrrolide ligands in the palladium(II) complexes 5 a-c, 6 b, and 6 c, and to the formation of rigid chiral C(2)-symmetric systems as shown by X-ray diffraction studies. The formation of the conjugated system of double bonds in
从已知的2,5-双(三甲基氨甲基)吡咯二碘化物(1)。1与NaCN在二甲亚砜中的反应干净地得到2,5-双(氰基甲基)吡咯(2),然后将其与氨基醇环化,得到2,5-双(2-恶唑啉基甲基)吡咯3 ac(3 a:双[2-(4,4'-二甲基-5-氢恶唑基)甲基]吡咯; 3 b:(S,S)-双[2-(4-异丙基-4,5-二氢恶唑基)甲基]吡咯; 3 c :(S,S)-双[2-(4-叔丁基-4,5-二氢恶唑基)甲基]吡咯)。用一摩尔当量的tBuLi进行3 ac的金属化,然后与化学计量的[PdCl(2)(cod)](cod =环辛二烯)反应,得到钯(II)配合物4 ac。尽管在晶体学上表征的配合物4a中的N-供体原子的排列几乎理想地是正方形平面,但是配体中的所有三个杂环都被扭曲出配位平面,从而导致了配合物的手性构象。试图在溶液中以200 K(NMR)冻结这两个构象异构体的尝试失败了,这表明构象消旋作用的激活势垒明显低于10