Unexpected direct dilithiation of a prochiral phosphine borane.

Dimethylphenylphosphine borane is readily deprotonated at both methyl groups with tBuLi and (R,R)-TMCDA to the corresponding dilithiated Lewis base adduct, featuring an intriguing structural motif with stabilising Li-H interactions.

A monolithiated and its related 1,3-dilithiated allylsilane: syntheses, crystal structures, and reactivity.

Treatment of Me2Si(CH2CH=CH2)(CH2NC5H10) with 1 or 2 equiv of t-BuLi afforded the mono- or dilithiated allylsilanes, which crystallize as a tetramer and a hexamer from pentane. The product selectivity in trapping reactions is influenced by the ability of both the solvent and the electrophile to coordinate the lithium center.