A precoordination complex of 1,2,3-trimethyl-1,3,5-triazacyclohexane with tert-butyllithium as key intermediate in its methylene group deprotonation.

Alpha-lithiated tertiary methylamines are important building blocks in all fields of chemistry, such as for the synthesis of new ligand or catalyst systems. However, the access to these compounds is still limited and the reaction mechanism, in general, not fully understood. We present herein X-ray diffraction analyses of organolithium compounds with 1,2,3-trimethyl-1,3,5-triazacyclohexane (1), such as a precoordination adduct of tert-butyllithium, [(tBuLi)(3)C(6)H(15)N(3)], which represents a potential intermediate of the lithiation of the methylene group of this ligand. By means of molecular structures and computational studies, the regioselectivity of this deprotonation reaction can be understood. Furthermore, the tBuLi adduct gives a hint to an alternative deaggregation process of organolithium compounds.