Diencarbonsäuren aus 1,3-dienen und CO2 durch C-C-verknüpfung an nickel(0)
作者:H. Hoberg、D. Schaefer、B.W. Oster
DOI:10.1016/0022-328x(84)80144-8
日期:1984.5
react with 1,3-dienes in the presence of CO2 to give nickela carboxylates. The influence of ligands and temperature on the regioselectivity of the CC bond formation is elucidated. In some cases the nickela carboxylates undergo reductive elimination under the influence of maleicanhydride, and the coupled diene/CO2 moiety rearranges to give the diene carboxylic acid. A possible reaction sequence is
(Lig)Ni 0系统在CO 2的存在下与1,3-二烯反应生成羧酸镍。阐明了配体和温度对CC键形成区域选择性的影响。在某些情况下,镍的羧酸盐在马来酸酐的影响下经历还原消除,并且偶合的二烯/ CO 2部分重排以得到二烯羧酸。讨论了可能的反应顺序。
L'eldanolide, phéromone des glandes alaires de la pyrale de la canne à sucre, eldana saccharina (wlk.): structure et synthèse de ses deux énantiomères
The isolation and structure determination of eldanolide, the wing gland pheromone of the male African Sugar Cane Borer, Eldana saccharina (Wlk.) is described. The absolute configuration was determined as (3S, 4R) by comparison of the CD spectra of the natural pheromone with both synthetic enantiomers.
Prins cyclization to tetrahydrofuran units of polyether antibiotics: Remarkable siloxy effect for stereocontrolled cyclization
作者:Koichi Mikami、Masaki Shimizu
DOI:10.1016/s0040-4039(00)60962-0
日期:1992.10
A novel route to substituted tetrahydrofurans is described, which is based on the Lewis acid-promoted Prins cyclization with side chain formation of CC bond. Bishomoallylic silyl ethers, rather than the (chloro)benzyl ethers and esters, provide selectively tetrahydrofurans, indicating the siloxy effect for facilitating the cyclization.
Negatively substituted halomethanes were allylated easily by allyltin compounds via radical chain reaction involving SH′ process. Aryl, aralkyl, and alkyl halides underwent similar chain reactions only when the tin compound was charged in excessive amounts.
Stereoselective Selenolactonization by Superelectrophilic Benzeneselenenyl Triflate
作者:Shizuaki Murata、Toshiyasu Suzuki
DOI:10.1246/cl.1987.849
日期:1987.5.5
Benzeneselenenyl triflate is prepared from benzeneselenenyl chloride and silver trifluoromethanesulfonate. It performs selenium-induced cyclization of β,γ-, γ,δ-, and δ,ε-unsaturated carboxylic acids.