The Lithiation Reactivity and Selectivity of Differentially Branched Alkyldiphenylphosphine Oxides - A Simple and Versatile Approach to ortho-Functionalized Arylphosphine Oxides
2015
Abstrakt
Alkyldiphenylphosphine oxides typically undergo alpha-deprotonation with alkyllithium reagents. Here, the lithiation of differentially branched alkyl-diphenylphosphine oxides was investigated and a diverse, but predictable reactivity was found. gamma-Branched derivatives undergo selective directed ortho-metalation (DoM) using butyllithium and TMEDA as an additive.
With decreasing degree of gamma-branching alpha-lithiation becomes predominant. The ortho-phosphinoyllithium intermediates are subject to functionalization and C-C bond forming reactions, thus providing a convenient approach to new phosphine oxides and phosphine-borane complexes, which have a good potential for an approach to new ligands for catalysis.