Titanocene(III) mediated radical cyclization of α-bromo carbonyl compounds: synthesis of tri-substituted tetrahydrofurans
作者:Samaresh Jana、Chandrani Guin、Subhas Chandra Roy
DOI:10.1016/j.tetlet.2004.12.079
日期:2005.2
has been developed for the construction of synthetically important tri-substituted tetrahydrofuran derivatives from bromo-alkenes and bromo-alkynes by radicalcyclization reactions using the radical initiator Cp2TiCl, generated in situ from commercially available titanocene dichloride and Zn dust in tetrahydrofuran under argon.
The indirect electroreduction of unsaturated α-bromoesters using Ni(II) complexes as electron-transfer mediators is achieved in N,N′-dimethylformamide by constant current electrolysis between a cathode and a sacrificial anode in a diaphragmless cell. Cyclic compounds are obtained in moderate to good yields in conditions that avoid the usual preparation using organotin reagents.
Electrochemical Catalytic Cyclization Reactions Using Environmentally Friendly Methodologies
作者:E. Duñach、M. J. Medeiros、S. Olivero
DOI:10.1149/2.016307jes
日期:——
The electrochemical intramolecular cyclisation of bromoalkoxylated derivatives 1 was carried out using Ni(II) complexes as the catalysts in ethanol solutions by constant-current electrolysis in one-compartment cell in the absence of sacrificial anodes as an environmentallyfriendly system. The reduction of the substrates proceeds via one-electron cleavage of the carbon–bromine bond to form radical-type