H-1 and C-13 NMR assignments for new heterocyclic TAM leuco dyes, (2Z,2 ' E)-2,2 '-(2-phenyl propane-1,3-diylidene) bis(1,3,3-trimethylindoline) derivatives. Part II

Abstract

The H-1 and C-13 NMR spectra of the novel heterocyclic Leuco-TAM dyes, (2Z,2'E)-2,2'-(2-phenyl propane-1,3-diylidene) bis(1,3,3-trimethylindoline) derivatives 1-4 as precursors of triarylmethane (TAM)+ (Malachite Green FB-analog) dyes were completely assigned by 1D and 2D NMR experiments, including DEPT, COSY, HSQC, HMBC, and NOESY. Especially, the diastereotopic gem-dimethyl protons at the C3 and C3' positions of the FB rings were definitively assigned. The (Z,E) isomers adopt the energetically favored three-bladed propeller conformation in solution. Copyright (c) 2008 John Wiley & Sons, Ltd.