This thesis outlines work carried out over the past three years concerning the development of an experimentally simple, sustainable catalytic method for the functionalisation of pyridines by means of a zinc nitrate based Lewis acid. It encompasses reaction discovery and optimisation, determination of the scope of the method through nucleophile and substrate screens as well as investigations into the mechanism by which the reaction takes place. Chapter 1 gives a general overview of the industrial relevance of pyridine functionalisation as well as the synthetic methods for the synthesis of ring functionalised pyridines, covering traditional stoichiometric aromatic substitution methods, transition metal catalysed cyclisations, standard catalytic methods for the functionalisation of pyridines: Buchwald-Hartwig and Ulmann reactions, as well as a précis of some recent transition metal catalysed methods for C-H functionalisation of pyridines. It also reviews classical and transition metal catalysed methods for conjugate addition and Diels–Alder reactions of vinylpyridines. Chapter 2 involves reaction discovery for the use of Lewis acids for the activation of pyridines towards nucleophilic aromatic substitutions, reaction optimisations, kinetic investigations and an examination of the scope in substrates and incoming groups. Chapter 3 investigates the use of Lewis acids for the activation of vinylpyridines toward conjugate addition, reaction optimisations, investigations into scope of incoming groups and subsequent optimisation studies for each. The method is also extended to Diels–Alder cyclisations, for which the reaction is also optimised.