Search results
Results from the WOW.Com Content Network
The reaction is highly stereospecific in the sense that the double bond stereochemistry is generally transferred to the relative configuration of the epoxide with essentially perfect fidelity, so that a trans-olefin leads to the stereoselective formation of the trans-2,3-substituted epoxide only, as illustrated by the example above, while a cis ...
The initial result was disappointing as reaction of CpTa(=CH−t−Bu)Cl 2 with ethylene yielded only a metallacyclopentane, not metathesis products: [44] But by tweaking this structure to a PR 3 Ta(CHt−bu)(Ot−bu) 2 Cl (replacing chloride by t-butoxide and a cyclopentadienyl by an organophosphine, metathesis was established with cis-2 ...
Because the cis–trans and E–Z systems compare different groups on the alkene, it is not strictly true that Z corresponds to cis and E corresponds to trans. For example, trans-2-chlorobut-2-ene (the two methyl groups, C1 and C4, on the but-2-ene backbone are trans to each other) is (Z)-2-chlorobut-2-ene (the chlorine and C4 are together ...
For a nondissociative pathway, reductive elimination occurs from the four-coordinate system to afford a two-coordinate complex. If the eliminating ligands are trans to each other, the complex must first undergo a trans to cis isomerization before eliminating. In an associative mechanism, a ligand must initially associate with the four ...
For monoalkenes, the configuration is often indicated by the prefixes cis- (from Latin "on this side of") or trans- ("across", "on the other side of") before the name, respectively; as in cis-2-pentene or trans-2-butene. The difference between cis-and trans-isomers
Acetylene (systematic name: ethyne) is the chemical compound with the formula C 2 H 2 and structure H−C≡C−H.It is a hydrocarbon and the simplest alkyne. [8] This colorless gas is widely used as a fuel and a chemical building block.
Cyclohexene derivatives, such as imines, epoxides, and halonium ions, react with nucleophiles in a stereoselective fashion, affording trans-diaxial addition products. The term “Trans-diaxial addition” describes the mechanism of the addition, however the products are likely to equilibrate by ring flip to the lower energy conformer, placing the new substituents in the equatorial position.
However, as is the case with the overall mechanism, the pathway of alkene approach is also debated. [8] One proposed substrate approach pathway - Note: Substrates are perpendicular to the plane of the catalyst. The ease with which Jacobsen's catalyst selectively epoxidizes cis-alkenes has been difficult to replicate with terminal and trans ...