The condensation can be carried out in organic solvents, particularly non-polar solvents such as toluene, xylene or tetrahydrofuran and, optionally, in the presence of a catalyst, acid catalysts, and especially acid catalysts such as fluorinated organic acid catalysts, p-toluenesulfonic acid, chloroacetic acid or acid aluminic acid): The synthetic routes to naphthopyrans (V) from proper derivative