Substitution reactions of 2-benzenesulphonyl cyclic ethers with carbon nucleophiles
作者:Dearg S. Brown、Maurizio Bruno、Raymond J. Davenport、Steven V. Ley
DOI:10.1016/s0040-4020(01)81323-5
日期:1989.1
Direct substitution of 2-benzenesulphonyl cyclic ethers was studied using a variety of carbon nucleophiles. These nucleophiles included organozinc reagents (derived from aryl, vinyl and alkynyl Grignard reagents) or silyl enolethers, silyl ketene acetals, allylsilanes and trimethylsilylcyanide in the presence of aluminum chloride. A general selectivity for the formation of the trans-product was observed
A nitrite-catalyzed ring contraction reaction of substituted tetrahydrofurans by oxidation of bromide under aerobic conditions as a dehydrogenative dual functionalization was developed to provide 2-acyltetrahydrofurans in good yields. On the other hand, the oxidation reaction of 1-substituted isochromans occurred via the bromohydroxylation to give 1-(dibromoalkyl)-1-hydroxyisochromans in high yields
Ligand-Based Control of Nickel Catalysts: Switching Chemoselectivity from One-Electron to Two-Electron Pathways in Competing Reactions of 4-Halotetrahydropyrans
作者:Taylor A. Thane、Elizabeth R. Jarvo
DOI:10.1021/acs.orglett.2c01335
日期:2022.7.22
which ligands promote and suppress competing mechanisms. We evaluate ligand-based modulation of catalyst preference for one- or two-electron pathways employing 4-halotetrahydropyrans as model substrates that can undergo divergent reaction pathways. Chemoselectivity for one- or two-electron oxidative addition is predicted by ligand class. Phosphine-ligated nickel catalysts favor closed-shell oxidative addition