We adapted the unification procedure of Huet for a family of explicit substitutions (ES) calculi. The novelty of this adaptation is that it works for calculi with explicit substitutions that belong to the paradigm known as “at a distance”. In this kind of calculi, which have attracted quite some attention due to their simplicity and applicability, the substitution operation is not propagated ov...

the facile and high yield synthesis of a new series of dibenzophenones in the presence of polyphosphoric acid (ppa) together with their cyclization to corresponding moni and dixanthones are described. the aromatic nucleophilic substitution of these new compounds are also studied.