The Lithiation Reactivity and Selectivity of Differentially Branched Alkyldiphenylphosphine Oxides - A Simple and Versatile Approach to ortho-Functionalized Arylphosphine Oxides

• Published in: Advanced synthesis & catalysis Vol. 357; no. 4; pp. 793 - 799
• Main Authors: Mahamulkar, Shraddha G., Císařová, Ivana, Jahn, Ullrich
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 09.03.2015; WILEY‐VCH Verlag; Wiley
• Subjects: Additives; Bonding; Branched; Butyllithium; Catalysis; Chemistry; Chemistry, Applied; Chemistry, Organic; Derivatives; Ligands; lithiation; nucleophilic substitution; organolithium reagents; Oxides; phosphine oxides; phosphine-borane complexes; Physical Sciences; Science & Technology; Synthesis; ASYMMETRIC CATALYSIS; ORGANIC-SYNTHESIS; PHOSPHORUS; REAGENTS; CARBANION TRANSMETALATION; phosphineborane complexes; DIRECTED ORTHO-METALATION; lithiation; phosphine oxides; LIGANDS; nucleophilic substitution; TRIPHENYLPHOSPHINE OXIDE; CHEMISTRY; organolithium reagents
• ISSN: 1615-4150; 1615-4169
• DOI: 10.1002/adsc.201400861

Alkyldiphenylphosphine oxides typically undergo α‐deprotonation with alkyllithium reagents. Here, the lithiation of differentially branched alkyldiphenylphosphine oxides was investigated and a diverse, but predictable reactivity was found. γ‐Branched derivatives undergo selective directed ortho‐metalation (DoM) using butyllithium and TMEDA as an additive. With decreasing degree of γ‐branching α‐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.