75589-94-5

Upstream product

• 768-33-2 phenyldimethylsilyl chloride 
• 18001-18-8 allyldimethylphenylsilane 
• 3839-31-4 dimethyl(phenyl)silyllithium 
• 74-86-2 acetylene 
• 74-88-4 methyl iodide 
• 74-99-7 prop-1-yne 

Downstream Products

• 114431-75-3 (2RS,3RS)-2--1-methylpropyl benzoate 

Relevant academic research and scientific papers

Z -selective alkene isomerization by high-spin cobalt(II) complexes

The isomerization of simple terminal alkenes to internal isomers with Z-stereochemistry is rare, because the more stable E-isomers are typically formed. We show here that cobalt(II) catalysts supported by bulky β-diketiminate ligands have the appropriate kinetic selectivity to catalyze the isomerization of some simple 1-alkenes specifically to the 2-alkene as the less stable Z-isomer. The catalysis proceeds via an "alkyl" mechanism, with a three-coordinate cobalt(II) alkyl complex as the resting state. β-Hydride elimination and [1,2]-insertion steps are both rapid, as shown by isotopic labeling experiments. A steric model explains the selectivity through a square-planar geometry at cobalt(II) in the transition state for β-hydride elimination. The catalyst works not only with simple alkenes, but also with homoallyl silanes, ketals, and silyl ethers. Isolation of cobalt(I) or cobalt(II) products from reactions with poor substrates suggests that the key catalyst decomposition pathways are bimolecular, and lowering the catalyst concentration often improves the selectivity. In addition to a potentially useful, selective transformation, these studies provide a mechanistic understanding for catalytic alkene isomerization by high-spin cobalt complexes, and demonstrate the effectiveness of steric bulk in controlling the stereoselectivity of alkene formation.

Cobalt-catalyzed isomerization of 1-alkenes to (E)-2-alkenes with dimethylphenylsilylmethylmagnesium chloride and its application to the stereoselective synthesis of (E)-alkenylsilane

Treatment of 1-alkenes with dimethylphenylsilylmethylmagnesium chloride in the presence of a cobalt-NHC complex in dioxane at 50°C or higher provides the corresponding (E)-2-alkenes selectively. The isomerization is applicable to the stereoselective synth

Cationic rearrangements controlled by the presence of a silyl group

1,1-Disilylcarbinols having two alkyl groups on the adjacent carbon atom react with thionyl chloride in sulfur dioxide to give the product in which one of the alkyl groups has migrated towards the two silyl groups, and one of the silyl groups has been removed from the resultant cation. The reaction is seen in ring-expansion, as in the conversion of cyclohexylbis[dimethyl(phenyl)silyl]carbinol (7) into 1-dimethyl(phenyl) silylcycloheptene (11), and in open chains, as in the conversion of 1,1-bis[dimethyl(phenyl)silyl]-2-methylpropanol (26) into (E)- and (Z)-2-dimethyl(phenyl)silylbut-2-ene (27). Phenyldimethylsilyllithium reacts with pinacolone to give the α-silyl carbinol (44), which rearranges in the same way to give 2,3-dimethylbut-2-ene (46), effectively achieving a pinacolone-to-pinacol rearrangement.

The Silylcupration of Acetylenes: a Synthesis of Vinylsilanes

Bis(dimethylphenylsilyl)copper-lithium (1) reacts with hex-1-yne, propyne, acetylene itself, phenylacetylene, and hex-3-yne to give the products of syn addition of the dimethylphenylsilyl group and the copper.The resultant vinylcopper reagents react with a variety of electrophiles, such as the proton, iodine, acyl and alkyl halides, enones, and epoxides, to give vinylsilanes.With the terminal alkynes, the silyl group becomes attached with a high level of regioselectivity to the terminal carbon atom, with the result that the final products are 2,2-disubstituted vinylsilanes.

Reaction of a Silyl-Copper Reagent with Acetylenes: a New Synthesis of Vinylsilanes

A silyl-cuprate reagent adds regioselectively to terminal acetylenes and the intermediate (3) reacts with electrophiles to give 2,2-disubstituted vinylsilanes.