This thesis describes the application of complexes of heavier alkaline earth metals to the intramolecular hydroalkoxylation/cyclisation of alkynyl and allenyl alcohols and in addition, to the hydroamination of polyunsaturated arenes. Cyclisation of alkynyl alcohols was achieved using [Ae{N(SiMe3)2}2] (Ae = Ca, Sr, Ba) in the formation of five- and six-membered enol ethers. The cyclisations produced mixtures of the possible endo- and exocyclic enol ether products, rationalised as a consequence of alkyne/allene isomerisation. Although a ‘catalyst of choice’ could not be deduced, [Ba{N(SiMe3)2}2] proved highly effective in these cyclisations. Extension of the hydroalkoxylation towards tandem C−O/C−C formation was attempted with dialkynyl alcohols but in all cases led to monocyclisation of the substrates. Catalytic tandem C−N bond-forming reactions have been successfully applied to the double hydroamination of polyunsaturated arenes using heteroleptic complexes of the type [LAe{N(SiMe3)2}(THF)n] (Ae = Ca, Sr, Ba). Chemo- and regioselective hydroamination reactions are coupled in sequence to construct tetrahydroisoquinoline frameworks. The amine scope of these reactions was determined and results have shown that these regioselective transformations occur under significant stereoelectronic control.