The present thesis describes the synthetic potential of 1,3-bis-silyl-enol ethers. They undergo regioselective cyclocondensation reactions with simple substrates providing various complex carba- and heterocycles. A new type of formal [3+3]-cyclization reaction with 2,4,6-tris(trifluoromethyl)-1,3,5-triazine is described. The mechanism was studied by the isolation of an unusual bicyclic intermediate. New and promising candidates for UV-A/B filters have been synthesized and analyzed.