97416-68-7Relevant academic research and scientific papers
Development of a Palladium-Catalyzed Process for the Synthesis of Z-Alkenes by Sequential Sonogashira–Hydrogenation Reaction
Hancker, S?ren,Neumann, Helfried,Beller, Matthias
, p. 5253 - 5259 (2018)
A novel and selective sequential one-pot protocol for the synthesis of Z-alkenes via Sonogashira–semihydrogenation is reported. The efficiency of the methodology is increased by utilizing PdCl2/BuPAd2 as homogeneous catalyst for the Sonogashira coupling and subsequently transforming the transition metal complex into a heterogeneous Pd hydrogenation catalyst. This methodology represents one of the rare examples directly combining homogeneous and heterogeneous catalysis.
Unequivocal experimental evidence for a unified lithium salt-free wittig reaction mechanism for all phosphonium ylide types: Reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived products
Byrne, Peter A.,Gilheany, Declan G.
supporting information; experimental part, p. 9225 - 9239 (2012/07/14)
The true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized, and stabilized): there is consistently increased selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving aldehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom substituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all Li salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey, and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a cooperative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.
Regiochemistry and Stereochemistry of Nickel-Promoted, Carbon-Carbon Bond-Forming Reactions of Cyclic Sulfur Compounds
Tiecco, Marcello,Tingoli, Marco,Wenkert, Ernest
, p. 3828 - 3831 (2007/10/02)
Reaction of methylmagnesium iodide and phenylmagnesium bromide with thianaphthene, dibenzothiophenone, thianthrene, and 2,3-dihydrothiapyran in the presence of nickel dichloride have been shown to yield, regioselectively in most cases, ring-opened products in which the carbon-sulfur bonds have been replaced by carbon-carbon bonds.Stereospecific carbon-carbon bond formation has taken place in the reactions of thianaphthene and 2,3-dihydrothiapyran, the products having maintained the cis-olefin configuration of the starting sulfur compounds.Isomerization into the more stable compounds has been observed in some cases.
