Copper-catalyzed conjugate additions of organozirconocenes. Synthetic and mechanistic studies.
作者:Peter Wipf、Wenjing Xu、Jacqueline H. Smitrovich、Roman Lehmann、Luigi M. Venanzi
DOI:10.1016/s0040-4020(01)85058-4
日期:1994.2
broad range of functional groups are tolerated in the conjugate addition process. Unsaturated N-acyl oxazolidinones give high diastereoselectivities for the formation of the new asymmetric carbon. The resulting zirconium enolates can be used for tandem aldoladdition reactions to aldehydes. Depending on the type of copper salt used, slow or fast formation of copper mirror occurs, but no intermediate
在3–10 mol%的Cu(l)盐(例如CuBr·S Me 2或CuCN)存在下,烷基锆茂金属很容易添加到α,β-不饱和酮,醛和砜中。反应产率对路易斯酸和碱的存在敏感。在共轭加成过程中可以耐受立体位阻以及广泛的官能团。不饱和氮-酰基恶唑烷酮类对形成新的不对称碳具有高的非对映选择性。所得的烯醇锆可用于醛醇的串联醇醛加成反应。根据所用铜盐的类型,会发生缓慢或快速形成铜镜的现象,但是在光谱学上没有检测到中间的铜物种。因此,提出了一种机理,该机理涉及路易斯酸性的锆茂并烯的烯酮络合,然后烷基取代基的内球转移到螯合的Cu(l)上。
Oxidative rearrangement of 1,1-disubstituted alkenes to ketones
作者:Qiang Feng、Qian Wang、Jieping Zhu
DOI:10.1126/science.adg3182
日期:2023.3.31
to the ring expansion of highly strained methylene cyclobutane derivatives. Herein, we report a solution to this synthetic challenge by designing a Pd II /Pd IV catalytic cycle incorporating a 1,2-alkyl/Pd IV dyotropic rearrangement as a key step. This reaction, compatible with a broad range of functional groups, is applicable to both linear olefins and methylenecycloalkanes, including macrocycles.
Carbanionic Rearrangements of Halomethylenecyclobutanes. The Role of the Halogen
作者:Zhengming Du、Melissa J. Haglund、Lauri A. Pratt、Karen L. Erickson
DOI:10.1021/jo9810866
日期:1998.11.1
The carbanionic ring enlargement of (halomethylene)cyclobutanes to 1-halocyclopentenes has been extended to the fluoro analogues. At 180 degrees C, 3-hexyl-1-(fluoromethylene)cyclobutane provides better yields of rearranged product than the corresponding chloride, bromide, or iodide. At temperatures < 100 degrees C, the yield of ring-enlarged product follows the order I > Br > Cl, and the fluoride does not react. Experiments with labeled substrates show that, in general, the larger the halide and the higher the reaction temperature, the greater the preference for double migration over single migration as a mechanistic pathway. The trifluormethyl group is ineffective in promoting anionic rearrangement.
Enantio- and Regioselective Baeyer−Villiger Oxidations of 2- and 3-Substituted Cyclopentanones Using Engineered Bakers' Yeast
作者:Margaret M. Kayser、Gang Chen、Jon D. Stewart
DOI:10.1021/jo980737v
日期:1998.10.1
Lemoult, Stephanie C.; Richardson, Paul F.; Roberts, Stanley M., Journal of the Chemical Society. Perkin transactions I, 1995, # 2, p. 89 - 92
作者:Lemoult, Stephanie C.、Richardson, Paul F.、Roberts, Stanley M.