Taskspecific ionic liquids and onium salts have been used as solublesupports for peptide synthesis. These new supports combine easy monitoring, high loading capacities, large scale preparation, and homogeneous kinetics characteristics while keeping advantages of solid-phase synthesis including easy purification and workup. Careful structural design of these supports allowed for fine tuning of physical
Cobalt-Catalyzed Silylcarbonylation of Unactivated Secondary Alkyl Tosylates at Low Pressure
作者:Joan E. Roque Peña、Erik J. Alexanian
DOI:10.1021/acs.orglett.7b02117
日期:2017.9.1
catalytic preparation of silyl enol ethers from unactivated secondary alkyl tosylates is reported. An inexpensive cobalt catalyst is used under mild conditions with low pressures of carbonmonoxide. Nucleophilic, anionic cobaltcarbonyls facilitate the catalytic activation of a range of alkyl tosylates. The silylcarbonylation offers a practical approach to synthetically valuable silyl enol ethers from simple
Reduction of aldehydes with 2-propanol proceeded efficiently by catalysis with hydrous zirconium oxide to give the corresponding alcohols. Most ketones also were reduced efficiently, but conjugated or sterically hindered ketones resisted the reduction. The reduction was carried out with primary, secondary, or tertiary alcohols, and only secondary alcohols served as hydrogen donors. Kinetic experiments
4-Haloalkyoxytributyltin compounds are relatively unstable and on heating give the corresponding tetrahydrofuran compounds in quantitative amounts. The 5-haloalkoxytributyltin compounds are more stable but at higher temperatures they also decompose quantitatively to tetrahydropyran compounds.
Preparation of .alpha.,.beta.-unsaturated carbocyclic ketones by reacting an enol lactone with a carbanion generated by treatment of a methylphosphonate or a mono-substituted methylphosphonate with base.