A DFT study of the geometric, magnetic NMR chemical shifts and optical rotation properties of Tröger’s bases

A DFT computational study of Tröger’s bases and related compounds (TBs) has been used to satisfactorily explain their geometry (including the flexibility aspect), the 1H NMR chemical shifts of the endo/exo protons and their optical properties. The Cambridge Structural Database has been searched to collect 34 structures of TBs that have been analyzed with respect to the folding angle ϕ. The GIAO approach has been used to calculate the absolute shieldings of TB and a quinoline analogue providing an explanation for the dependence of the relative position of the endo/exo protons on the structure of the TBs. Finally, the specific rotations of several molecules related to TBs have been calculated at the B3LYP/6-311++G(2s,2p) level. The [α]D values are strongly dependent on relatively small structural variations.

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