transition-metal-catalyzed allylicsubstitution was examined. The oxygen atom of oxime acted as a reactive nucleophile in the reaction of a π-allyl palladium complex. In the presence of Pd(PPh3)4, the allylicsubstitution of oximes with allylic carbonate afforded the linear O-allylated oxime ethers selectively without a base. In contrast, the palladium-catalyzed reaction with allylic acetate proceeded smoothly
考察了肟作为亲核试剂在过渡金属催化的烯丙基取代中的活力。肟的氧原子在π-烯丙基钯配合物的反应中充当反应性亲核试剂。在Pd(PPh 3)4存在下,用碳酸烯丙酯进行肟的烯丙基取代,可选择性地得到线性的O-烯丙基化肟醚,而无需碱。相反,在存在K 2 CO 3或Et 2 Zn作为碱的情况下,钯与乙酸烯丙酯的反应顺利进行。通过使用钯(II)催化剂选择性地形成硝酮。在Pd(cod)Cl 2存在下通过与肟的氮原子反应,在无溶剂条件下,用乙酸烯丙酯将肟的烯丙基取代提供了N-烯丙基化的硝酮。
Synthesis of chiral oxime ethers based on regio- and enantioselective allylic substitution catalyzed by iridium–pybox complex
reactive nucleophile in the iridium-catalyzed allylicsubstitution of unsymmetrical substrates to give the branched oxime ethers. Among several chiral ligands evaluated, the iridium complex of pybox ligand having phenyl group catalyzed the allylicsubstitution of phosphates with high activity to form the branched oxime ethers with good enantioselectivities.