Refernces
10.1021/ol100240b
The study investigates the GaCl3- or InBr3-catalyzed cyclopropylmethylation of benzylic and allylic chlorides with cyclopropylmethylstannane. Cyclopropylmethylstannane acts as a reactant, while GaCl3 or InBr3 serves as the catalyst. The researchers found that in the presence of these catalysts, benzylic and allylic chlorides can readily couple with cyclopropylmethylstannane to form cyclopropyl ring systems. The intermediate of an active butenylgallium or -indium species was confirmed by NMR spectroscopy and X-ray analysis. The study also explored the scope of this system using various secondary benzylic chlorides and found that they furnished cyclopropylmethylated products in moderate to high yields. Additionally, the researchers attempted to isolate the butenylgallium species by complexation using external ligands and proposed a plausible reaction mechanism involving transmetalation, activation of alkyl chloride, and cyclization. The study concludes that this reaction system provides a new method for the synthesis of cyclopropyl ring systems and further investigation of its mechanism and synthetic application is underway.
10.1055/s-2002-19298
The study focuses on the equatorial preference in the GaCl3-promoted ethenylation of cyclic ketones. The main content of the research revolves around the use of trimethylsilylethyne and GaCl3 to ethenylate silyl enol ethers derived from substituted cyclohexanones. The reaction proceeds via carbogallation of gallium enolate and alkynylgallium, generating a bisgallio-intermediate that is protodegallated under acidic conditions to form α-enones. The study investigates the stereoselectivity of this reaction, which exhibits a bias for equatorial C–C bond formation, contrasting with the axial stereochemistry observed in enolate alkylation. The chemicals used serve to explore and understand the mechanism behind this novel ethenylation reaction, which has implications for the synthesis of compounds with quaternary α-carbon atoms and enolizable products. The purpose of these chemicals is to facilitate the ethenylation process and provide insights into the stereochemical outcomes of the reactions, which are of significant interest in the field of organic synthesis.
10.1002/anie.200803269
The research focuses on the cis-selective single-cleavage skeletal rearrangement of 1,6-enynes in metal-catalyzed cycloisomerizations, aiming to reveal the multifaceted character of the intermediates involved in these reactions. The study explores the factors controlling the selectivity in the rearrangement of 1,6-enynes, which can lead to different types of products depending on the catalyst used. The researchers concluded that the cis-selective single-cleavage rearrangement of enynes has revealed an unrecognized aspect of gold intermediates in cycloisomerization and related reactions of enynes, where reactions are generally stereospecific but become non-stereospecific in the presence of strongly electron-donating substituents. The chemicals used in the process include various 1,6-enynes, gold catalysts such as AuCl, AuCl(oTol3P), and cationic AuI catalysts, as well as other metal catalysts like PtCl4, GaCl3, and InCl3.