Synthesis and conformational behaviour of tri-3-methyltrianthranilides. A new example of spontaneous resolution and inclusion compound formation on crystallisation

The tri-3-methyltrianthranilide derivatives ($\text{7}$)–($\text{9}$) have been synthesised. Dynamic ¹H n.m.r. spectroscopy indicates that the $\text{N}$,$\text{N}$′,$\text{N}$″-trimethyl derivative ($\text{8}$) exists in solution as slowly ring inverting ($\text{16}$ ? $\text{16}$*) enantiomeric helical conformations. X-Ray crystallography shows that the $\text{N}$,$\text{N}$′-dimethyl-$\text{N}$″-benzyl derivative ($\text{9}$) undergoes spontaneous resolution when it crystallises as a 1:1 adduct from toluene. The host molecules adopt a helical conformation (Figure 1) within a lattice structure that contains chiral channels (Figure 2) occupied by guest solvent molecules.