Asymmetric Cycloaddition Reactions Catalyzed by Transition Metal Complexes
Asymmetric Cycloaddition Reactions Catalyzed by Transition Metal Complexes
复制标题
过渡金属配合物催化的不对称环加成反应
DOI：
10.5059/yukigoseikyokaishi.56.368
复制
发表时间：
1998
影响因子：
0.2
通讯作者：
Yoji Oderaotoshi
中科院分区：
文献类型：
--
作者：
S. Kanemasa;Yoji Oderaotoshi
反式螯合三齿配体（R，R）-4，6-二苯并呋喃二基-2，2 ' -双（4-苯基恶唑啉）和过渡金属高氯酸盐的阳离子水溶液配合物在环戊二烯Diels-Alder反应、硝酮环加成反应和重氮甲烷与3-烯酰基-2-恶唑烷酮的环加成反应中表现出优异的对映选择性。由高氯酸镍（II）六水合物制备的活性催化剂络合物具有三个水配体的八面体结构，并且它可以被分离和储存数月而不损失催化活性。由高氯酸镍（II）或高氯酸锌（II）制备的水络合物在Diels-Alder反应中产生高效的手性放大。这种显著的手性放大涉及两种机制：（1）DBFOX/Ph与Ni（II）离子之间的S4对称meso-2：1络合物的沉淀;（2）借助于基于水配体的氢键缔合形成1：1异手性络合物以产生稳定的meso寡聚体。
Cationic aqua complexes of a trans-chelating tridentate ligand, (R, R) -4, 6-dibenzofurandiyl-2, 2' -bis (4-phenyloxazoline), and transition metal (II) perchlorates are effective catalysts in the cyclopentadiene Diels-Alder reactions, nitrone cycloadditions, and diazomethane cycloadditions with 3-alkenoyl- 2-oxazolidinones to show excellent enantioselectivities. The active catalyst complex prepared from nickel (II) perchlorate hexahydrate has an octahedral structure with three aqua ligands, and it can be isolated and stored for months without loss of catalytic activity. The aqua complex prepared from Ni (II) or Zn (II) perchlorate results in highly effective chiral amplification in the Diels-Alder reaction. Two mechanisms for amplification are involved for this remarkable chiral amplification : (1) precipitation of S4-symmetric meso-2 : 1 complex between DBFOX/Ph and Ni (II) ion, and (2) associative formation of 1 : 1 heterochiral complexes by the aid of hydrogen bonds based on aqua ligands to produce stable meso oligomers.