Nickel-Phosphine Complex-Catalyzed Grignard Coupling. I. Cross-Coupling of Alkyl, Aryl, and Alkenyl Grignard Reagents with Aryl and Alkenyl Halides: General Scope and Limitations
(s)), aryl, and alkenyl Grignard reagents and nonfused, fused, and substituted aromatic halides and haloolefins. Limitations lie in sluggish reactions between alkyl Grignard reagents and dihaloethylenes. The most effective catalysts are [Ni(C6H5)2P(CH2)3P(C6H5)2}Cl2] for alkyl and simple aryl Grignard reagents, [Ni(CH3)2P(CH2)2P(CH3)2}Cl2] for alkenyl and allylic Grignard reagents and [NiP(C6H5)3}2-Cl2]
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.
Stereospecific Synthesis of <i>E</i>-Alkenes through Anti-Markovnikov Hydroalkylation of Terminal Alkynes
作者:Avijit Hazra、Jason Chen、Gojko Lalic
DOI:10.1021/jacs.9b04800
日期:2019.8.14
We have developed a method for stereospecificsynthesis of E-alkenes from terminal alkynes and alkyl iodides. The hydroalkylation reaction is enabled by a cooperative action of copper and nickel catalysts and proceeds with excellent anti-Markovnikov selectivity. We demonstrate the broad scope of the reaction, which can be accomplished in the presence of esters, nitriles, aryl bromides, ethers, alkyl
Reaction of α,α′ - bis(trimethylsiloxy) sulfides with low valent titanium reagents
作者:T.H. Chan、J.S. Li、T. Aida、David N. Harpp
DOI:10.1016/s0040-4039(00)86962-2
日期:1982.1
We have shown that low valent titanium reagents reductively couple α,α′ -bis-(trimethylsiloxy) sulfidees giving olefins in good yield. With unsymmetrical , mixed olefins are obtained suggesting an intermolecular pathway. Finally, we have demonstrated that -episulfide is quantitatively converted to -stilbene.
metathesis reactions allows for a stereoselective subsequent RuO4-catalyzed dihydroxylation. The sequence is concluded by an unusual kinetic resolution of the diastereomeric diols obtained in the oxidation reaction. As a consequence a variety of structurally diverse enantiomerically enriched diols are obtained. To the best of our knowledge the results summarized in this paper represent the first highly efficient