Synthesis of a protonated C2-symmetric N,N-chiral 'proton sponge'

Article abstract of DOI:10.1016/S0040-4039(98)00930-7

The hydrogen iodide salt of 1,8-bis-(N-benzyl-N-methylamino)naphthalene was synthesised as an 89 / 11 ratio of diastereomers in good yield. The structure of the major (±)-(R(N)R(N)/S(N)S(N)) diastereomer was determined by single crystal X-ray diffraction. The minor diastereomer is shown to be the meso-(R(N)S(N)) form by performing ¹H NMR n.O.e studies on isotopically desymmetrized 1-(N-benzyl-N-[¹³C]-methylamino)-8-(N'-benzyl-N'- methylamino)naphthalene (HI salt). The half-life of interconversion of meso and dl forms is less than 2 minutes in CD₂Cl₂ at ambient temperature.