Abstract: This invention relates to novel naphthopyrans having an oxygen-containing heterocyclic group F annelated on the i, j, or k side of the naphthopyran ring, having certain substituents at the 2, 5, and 6 positions of the naphthopyran ring. These naphthopyrans may have the formula (I) presented below: These compounds (I) have interesting photochromic properties. Also related to this invention are host materials that contain such naphthopyran compounds, and articles such as ophthalmic lenses or other plastic transparencies that incorporate the naphthopyran compounds.