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 (7)-(9) have been synthesised. Dynamic ¹H n.m.r. spectroscopy indicates that the N,N′,N″-trimethyl derivative (8) exists in solution as slowly ring inverting (16 ⇌ 16*) enantiomeric helical conformations. X-Ray crystallography shows that the N,N′-dimethyl-N″-benzyl derivative (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.