Aromatic nucleophilic substitution. Part 2. Preparation of novel 3‐substituted xanthone and thioxanthone derivatives

Abstract

AbstractThe novel 3‐nitro‐9‐oxo‐9H‐xanthene‐ and 3‐nitro‐9‐oxo‐9H‐thioxanthene‐l‐carboxylic acids 2a–d were prepared by intramolecular acylation of 3‐aryloxy‐ and 3‐arylthio‐5‐nitrophthalic anhydrides 1 (Scheme). The 3‐nitro group was readily substituted by O‐ and S‐nucleophiles and halide and azide ions to give a range of 3‐substituted thioxanthone derivatives 3 with varied λmax.