Simulation of 13C nuclear magnetic resonance spectra of indoles

Abstract

Linear models are developed to predict the 13C NMR chemical shifts of carbons in indole moieties based on a critical review. These models fill a gap in the spectral simulation database which is used to simulate the 13C NMR spectra of a wide range of organic compounds, illustrating that this is a viable method for the expansion of the database. The models are based on calculated numerical parameters (descriptors) which encode the topological and topological-electronic environments of the eight indole carbons. The 56 indoles in the reference set have a mean r.m.s. error of 0.93 ppm and the 42 indoles in the prediction set have an error of 2.04 ppm. The spectral error for N-substituted indoles is higher than that of N-unsubstituted indoles.