Nickel-Catalyzed Alkylation or Reduction of Allylic Alcohols with Alkyl Grignard Reagents
作者:Bo Yang、Zhong-Xia Wang
DOI:10.1021/acs.joc.0c00008
日期:2020.4.3
selective alkylation and reduction of allylicalcohols with alkyl Grignard reagents were performed. The reaction using Ni(dppe)Cl2 as the catalyst resulted in the cross-coupling of allylicalcohols with primary alkyl Grignard reagents and cyclopropylmagnesium bromide. The reaction catalyzed by the combination of Ni(PCy3)2Cl2 and dcype led to the reduction of allylicalcohols. Secondary alkyl Grignard
The reduction of the carbonyl group in acylated trifluoroethyl alkanesulfonates follows the Felkin-Ahn selectivity, and the so-formed diastereomeric β-hydroxysulfonyl intermediates undergo syn- and anti-fragmentation, depending on the reaction conditions. In effect, isomeric E- and Z-alkenes are formed in a stereodivergent manner, which mimics the mechanistic manifold of the Peterson olefination.
SN2-selective Grignard coupling with primary allylic diphenylphosphates was successfully achieved using Ni or Fe catalyst. In sharp contrast, a catalytic amount of CuCN·2LiCl promoted a SN2′-selective coupling reaction. In the presence of the copper catalyst, stereochemically homogeneous γ- disubstituted allyl Grignardreagents reacted at the less substituted allylic terminus (α-position) with an allylic diphenylphosphate
使用Ni或Fe催化剂成功地实现了S N 2-选择性格利雅(Grignard)与伯烯丙基二苯基磷酸酯的偶联。与之形成鲜明对比的是,催化量的CuCN·2LiCl促进了S N 2'-选择性偶联反应。在铜催化剂的存在下,立体化学均一的γ-二取代的烯丙基格氏试剂在较少取代的烯丙基末端(α-位)与烯丙基磷酸二苯酯选择性地反应,而不会失去双键的几何形状。
Olefination with Sulfonyl Halides and Esters: <i>E</i>
-Selective Synthesis of Alkenes from Semistabilized Carbanion Precursors
Sulfur‐based olefination with Horner–Wadsworth–Emmons‐type mechanism is systematically studied. Nonstabilized and semistabilized carbanion precursors react with carbonyl compounds giving good yields of olefins, and for the latter reagents E isomers of alkenes predominate.
The invention of radical reactions. Part XXVII. Modified Julia Synthesis of Olefins Using radical deoxygenation.
作者:Derek H.R. Barton、Catherine Tachdjian
DOI:10.1016/s0040-4020(01)88251-x
日期:1992.1
Xanthate derivatives of beta-hydroxy sulfones react with methyl radicals generated from the photolysis of N-acetyloxy-2-thiopyridone lo give the corresponding olefin. Under identical conditions a secondary alcohol is transformed into its thiopyridyl derivative.