During this master thesis the enantioselective syntheses of trans-2,3,dihydrobenzofurans via in situ generated o-quinone methides and ammonium ylides were investigated. The 2,3-dihydrobenzofuran skeleton is present in many bioactive molecules. There are different ways to synthesize trans-2,3-dihydrobenzofurans like radical cyclizations, electro- and anionic cyclizations, Lewis acid catalyzed reactions, biomimetic couplings or transition metal catalyzed processes. Often harsh reaction conditions, inadequate yields, poor chemo- and/or stereoselectivities or arduous purifications are reported therefore. The herein developed (4+1) cycloaddition with in situ generated o-quinone methides and ammonium ylides showed high enantio- and diastereoselectivities. o-Quinone methides are biological active, highly reactive intermediates, which are usually not isolable and therefore formed in situ. The common way to generate o-quinone methides are thermal and base initiation and typical reactions are 1,4-additions or cycloadditions. Ylides are synthetically important for olefinations, cyclizations and rearrangements. Combining these two unique reactivity trends allowed for the development of a useful method to generate trans-2,3-dihydrobenzofurans. The synthesis strategy was simple and the Cinchona alkaloids were easy available chiral leaving groups. This strategy also showed a broad application scope. Computed energy profiles yielded information about the mechanism and illustrated the high tras-selectivity.