Synthesis, Conformation and Chiroptical Properties of Diaryl Esters of Tartaric Acid

Previously unknown diaryl esters of l-tartaric acid have been synthesized. Their conformations have been studied by DFT calculations, NMR and circular dichroism spectroscopy in solution, as well as by X-ray diffraction in the crystalline state. The four-carbon tartrate chain of diaryl esters was found to be extended in all cases, with a higher degree of nonplanarity in the crystals. Dinaphthyl tartrates show unusually strong exciton Cotton effects (A = −228 for di-1-naphthyl l-tartrate) due to the coupling of allowed 1B_b transitions in naphthyl chromophores, despite the acyclic structure and significant distance (over 10 Å) between the two chromophores.