13C-NMR and 1H-NMR chemical shifts in a correlation analysis of benzotriazole derivatives active as plant growth regulators

Following preliminary observations on auxin‐like activity of several 1‐ and 2‐substituted benzotriazole isomers, a few new derivatives have been synthesized and tested. In attempting to quantify by QSAR the structural properties of a large set of compounds and with the aim to rationalize the structure‐activity relationships taken into account in a previous study by a set of indicator variables, attention was turned to the analysis of 13C‐NMR and 1H‐NMR chemical shifts relative to the substituent carbon atom attached on the nitrogen of the benzotriazole ring. The 13C‐NMR chemical shift can be useful as an independent parameter in QSAR. Considerations of the general applicability of sigma inductive constants for predicting physicochemical properties of complex heteroaromatic systems such as those under study are discussed. Finally it is shown that there are important electronic and steric components which play a major role in promoting the auxin‐like activity of compounds under examination. Copyright © 1988 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim