Radical Deoxygenation of Xanthates and Related Functional Groups with New Minimalist N-Heterocyclic Carbene Boranes
作者:Shau-Hua Ueng、Louis Fensterbank、Emmanuel Lacôte、Max Malacria、Dennis P. Curran
DOI:10.1021/ol101015m
日期:2010.7.2
Minimalist N-heterocycliccarbeneboranes 1,3-dimethylimidazol-2-ylideneborane and 2,4-dimethyl-1,2,4-triazol-3-ylideneborane are readily available and have low molecular weights. They exhibit superior performance to first-generation NHC−boranes, providing improved yields in reductions of xanthates and related functional groups.
Complexes of Borane and N-Heterocyclic Carbenes: A New Class of Radical Hydrogen Atom Donor
作者:Shau-Hua Ueng、Malika Makhlouf Brahmi、Étienne Derat、Louis Fensterbank、Emmanuel Lacôte、Max Malacria、Dennis P. Curran
DOI:10.1021/ja804150k
日期:2008.8.1
Calculations suggest that complexes of borane with N-heterocyclic carbenes (NHC) have B-H bond dissocation energies more then 20 Kcal/mol less than free borane, diborane, borane-THF, and related complexes. Values are in the range of popular radical hydrogen atom donors like tin hydrides (70-80 Kcal/mol). The resulting prediction that NHC borane complexes could be used as radical hydrogen atom donors was verified by radical deoxygenations of xanthates by using either AIBN or triethylborane as initiator.