This thesis details investigations into the dearomatising cyclisation onto pyridines. Studies into the cyclisation of enolate or silyl enol ether nucleophiles onto a pyridine ring are described. Flexible hydrocarbon tethers and tethers incorporating either an oxygen or nitrogen atom were investigated and novel fused 6.5 and 6.6 bicyclic piperidines have been synthesised. A one-pot silyl enol ether or silyl ketene acetal formation and cyclisation procedure has been developed.