Exploring SmBr2-, SmI2-, and YbI2-Mediated Reactions Assisted by Microwave Irradiation
作者:Anders Dahlén、Edamana Prasad、Robert A. Flowers、Göran Hilmersson
DOI:10.1002/chem.200401320
日期:2005.5.20
hexamethyl phosphoramide (HMPA). The redox potential of YbI2 in tetrahydrofuran (THF) has been determined as -1.02+/-0.05 V (versus Ag/AgNO3) by cyclic voltammetry. A large selectivity difference in various reactions was observed depending on the redox potential of the LnX2 reagent. The morepowerful reductant, SmBr2, afforded mainly pinacol-coupling products of ketones whereas the weaker reductant YbI2 afforded
Reduction of imines was performed with zinc powder in 5% aq NaOH solutionwithout any organic solvents under mild conditions, and the corresponding amines were obtained in good yields.
We report the first direct and chemoselective reductive homocoupling reaction of secondary amides and cross-coupling reaction of secondary amides with ketones. This method relies on the direct generation of α-amino carbon radicals from amides.