R3Al, promote the Claisenrearrangement of allyl vinyl ether derivatives at room temperature under transfer of R or H as a nucleophile to the aldehydic carbon. Treatment of 1-butyl-2-propenyl vinyl ether with a hexane solution of Me3Al (1.0 M, 2.2 equiv) in CH2ClCH2Cl at 25 °C afforded 5-decen-2-ol (91% yield, E⁄Z=47⁄53), which was produced by the [3,3] sigmatropic rearrangement and successive methylation
有机铝化合物 R3Al 在室温下在 R 或 H 作为亲核试剂转移到醛碳的情况下促进烯丙基乙烯基醚衍生物的克莱森重排。在 25 °C 下,用 Me3Al(1.0 M,2.2 当量)在 CH2ClCH2Cl 中的己烷溶液处理 1-丁基-2-丙烯基乙烯基醚得到 5-癸烯-2-醇(产率 91%,E⁄Z=47⁄53 ),这是由 [3,3] sigmatropic 重排和连续甲基化产生的。还实现了炔基化、烯基化和氢化的重排。使用 Et2AlSPh(2.5 equiv)或 Et2AlCl(2.0 equiv)和 PPh3(2.2 equiv)的组合,在 25 °C 下获得了常规的 Claisen 重排产物或 γ,δ-不饱和醛(酮)。
Selenium stabilized carbanions. .alpha.-Lithio selenoxides as reagents for the synthesis of olefins, allyl alcohols, and dienes
作者:Hans J. Reich、Shrenik K. Shah、Flora Chow
DOI:10.1021/ja00516a026
日期:1979.10
Techniques for the preparation of a-lithio selenoxides have been developed. These reagents react cleanly with most aldehydes and ketones to give 0-hydroxy selenoxides, which can be thermolyzed to allyl alcohols or reduced to hI result of the limited acidifying power of the phenylseleno group, and the propensity of selenides to be fragmented upon treatment with powerful metalating agents. The substantially
A novel zirconium-catalyzed hydroalumination of olefins
作者:Ei-ichi Negishi、Tadao Yoshida
DOI:10.1016/s0040-4039(00)92757-6
日期:1980.1
hindered trialkylalanes, such as triisobutylalane, react with olefins at or below room temperature under the influence of a catalytic amount of Cl2ZrCp2 to effect hydroalumination of the olefins. The reaction can tolerate certain hetero-functional groups, such as OH, SPh, and Br, which tend to interfere with previously reported hydroalumination procedures.
In the presence of a catalytic amount of LiBH4, BH3 in THF selectively reduced the carbonylgroup of conjugated and unconjugated alkenones at –50 °C to quantitatively provide the corresponding alkenols on subsequent hydrolysis.
Structural, kinetics and mechanistic studies of transfer hydrogenation of ketones catalyzed by chiral (pyridyl)imine nickel(<scp>ii</scp>) complexes
作者:Robert T. Kumah、Nokwanda Tsaulwayo、Bheki A. Xulu、Stephen O. Ojwach
DOI:10.1039/c9dt00024k
日期:——
moments, elemental analysis and single crystal X-ray crystallography. The dinuclear dibromide nickel complexes dissociate into mononuclear species in the presence of strongly coordinating solvents. Compounds Ni1–Ni5 displayed moderate catalytic activities in the asymmetric transferhydrogenation (ATH) of ketones, but with low enantiomeric excess (ee%). Both mercury and substoichiometric poisoning tests pointed