Stereoconservative Formation and Reactivity of α-Chalcogen-Functionalized Vinyllithium Compounds from α-Bromo-vinylic Chalcogenides
作者:Antonio Braga、Gilson Zeni、Leandro de Andrade、Claudio Silveira
DOI:10.1055/s-1997-3227
日期:1997.5
Bromine/lithium exchange was performed upon treatment of α-bromo-vinylic chalcogenides with butyllithium in hexane at room temperature to provide α-chalcogen-vinyllithium intermediates quantitatively. Addition of electrophiles to the lithiated compounds gave the corresponding functionalized vinylic chalcogenides in good yields with retention of configuration.
The synthesis of regio- and stereoselective arylsubstitutedα,β-unsaturated aldehydes and ketones from activated allenes was achieved. This mild and non-metallic oxidation is exclusively driven by benign ambient air and triggered by visible light. The same starting materials under ideal anaerobic conditions led to the 2,3-diphenylselenation adduct with no trace of oxygenated products, demonstrating