AbstractThe17O NMR chemical shift data for a series of substituted 10‐methyleneanthrones and related 10‐alkylanthrones in acetonitrile solution at 75°C are reported. The17O NMR chemical shift value of 10‐methyleneanthrone is shielded byca. 35 ppm compared with that of anthraquinone. The chemical shifts of the 10‐methyleneanthrones range from 493 ppm for 10‐bromomethyleneanthrone to 440 ppm for 10‐diethylaminomethyleneanthrone. A correlation of the17O NMR chemical shifts of the 10‐substituted methyleneanthrones with σ+con