The organoselenium-induced ring-closure reactions of O-allyl oximes give cyclic iminium salts which react with water to afford isoxazolidines in good yield.
The [2,3] sigmatropic rearrangement of N-benzyl-O-allylhydroxylamines
作者:Stephen G. Davies、John F. Fox、Simon Jones、Anne J. Price、Miguel A. Sanz、Thomas G. R. Sellers、Andrew D. Smith、F??tima C. Teixeira
DOI:10.1039/b205323n
日期:2002.7.26
The rearrangement of a range of N-benzyl-O-allylhydroxylamines to the corresponding N-allylhydroxylamines upon treatment with n-BuLi in THF, followed by reduction to the corresponding N-allylamines, is described. Mechanistic studies of the transformation are consistent with an intramolecular [2,3] sigmatropic rearrangement.
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。
Utility of the Iridium Complex of the Pybox Ligand in Regio- and Enantioselective Allylic Substitution
[GRAPHICS]The viability of the iridium complex of pybox as chiral catalyst in allylic substitutions and the enantiosilective synthesis of branched products was studied. Among several chiral ligands evaluated, the iridium complex of pybox having a phenyl group catalyzed the reaction with high activity to form the branched amines with good enantioselectivities when hydroxylamine, amine, and aniline were employed as a nucleophile. The allylic substitution with oximes proceeded smoothly to give the branched oxime ethers with good enantioselectivities.