A solid state and theoretical study of the solvent effects controlling the mono-and di-lithiation of aromatic primary amines

摘要

Reaction of 1-naphtylamine, 4-tritylaniline or 4-methylaniline with two eqivalents of Bu~nLi in Et_2O or thf affords rare geminal N,N-dilithiates of general formula (L)_n·(Li_2NAr_10 (L = Et_2O, n = 6, Ar = 1-C_10H_7, C_6H_4-4-CPh_3 2; L = thf, n = 10, Ar = C_6H_4-4-Me 3). X-Ray crystal structure analyses reveal that the core (Li_14N_10~(6-) frameworks consist of two fused rhombic dodecahedra. Ab initio M.O.calculations on the mono-and di-lithiation of 1-naphthyl-amine and 4-methylaniline suggest that the selectivity with which polymethallation occuris solvent dependent and so help to rationalise the experimentally observed structures.