Diastereoselective ortho-lithiation of [5]ferrocenophanes

Planarly chiral ferrocene derivatives with bridged cyclopentadienyl rings are interesting ligands in asymmetric catalysis. A planar stereogenic unit is conveniently introduced by diastereoselective ortho-lithiation. The directed lithiation of several [5]ferrocenophane derivatives followed by quenching with chlorodiphenylphosphane led to planarly chiral ligands. The sense of diastereoselection was studied by computational methods. Absolute configuration of methoxy phosphane was determined by single crystal X-ray diffraction study.

Graphical abstractDiastereoselective ortho-lithiation of [5]ferrocenophane derivatives followed by a reaction with diphenylchlorophosphine affords new planar chiral ferrocenophane derivatives, potentially useful as ligands in asymmetric catalysis. Orientation of lithiations is rationalized with the help of quantum-chemical calculations.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► [5]Ferrocenophane derivatives are diastereoselectively ortho-lithiated. ► Double lithiation is possible on methylamino ferrocenophane derivative. ► Lithiation of methoxy ferrocenophane affords both diastereoisomers. ► Quantum-chemical calculations rationalize orientation of lithiations.