Unusual Coordination Pattern of the Lithium Center in a Chiral α-Lithiated Silicon Compound

Abstract

An understanding of how stereogenic centers can influence the construction of a new metalated chirality center requires profound investigations concerning coordination and aggregation effects. A racemic silicon-stereogenic aminomethoxysilane (2) was chosen as the starting compound, which is additionally equipped with a (trimethylsilyl)methylene bridge and an aminomethyl function. Metalation of 2 with tert-butyllithium led to the inversion-symmetric dimer (u-3)2, which shows an unusual coordination mode with intramolecular agostic C–H···Li interactions capping the three-coordinate trigonal-planar lithium centers. Compound 3 was characterized by X-ray crystallography and NMR spectroscopy in solution. Reaction of the lithiated intermediate 3 with chlorotrimethylstannane provided the first insight into the configurational stability of the metalated stereogenic center.