NMR assignment in regioisomeric hydroquinones

A set of regioisomeric pairs of tricyclic hydroquinones, analogues of antitumor 9,10‐dihydroxy‐4,4‐dimethyl‐5,8‐dihydroanthracen‐1(4H)‐one (1) and other derivatives, were synthesized and their regiochemistry and NMR spectra assigned by using 1H‐detected one‐bond (CH) HMQC and long‐range CH HMBC, in good agreement with theoretical O3LYP/Alhrichs‐pVTZ calculations. The 5‐hydroxymethyl derivatives (11, 15, 19) showed a 3JH, H coupling constant of methylene protons evidencing the presence of a seven‐membered intramolecular hydrogen bonded ring, not observed for the 8‐hydroxymethyl isomers. Copyright © 2011 John Wiley & Sons, Ltd. NMR assignment of regioisomeric hydroquinones was performed by using HMQC and HMBC experiments. The results are in good agreement with theoretical O3LYP/Alhrichs‐pVTZ calculations.