Starting from methyl-α-d-glucopyranoside the synthesis of protected 5-epi-valiolone could be carried out via a chiral-pool-synthesis using the Ferrier reaction as key-step. Valiolones are of biological and biochemical interest because of their possible function as an intermediate in the biosynthesis of acarbose, which is one of the most potent α-glucosidase-inhibitors and is commercially used for the treatment of diabetes mellitus. Also by this route the synthesis of an inositol substitued with a C₁-branch was realized. This substance has pharmacological potential as a new, so far untested glycosidase-inhibitor. In an alternative de-novo-synthesis, starting from p-benzoquinone, some biologically, biochemically and pharmacoligically interesting substances could be synthesized: Valiol and 1-epi-valiol are also possible intermediates of the acarbose-biosynthesis. These compounds could be synthesized for the first time and can now be used for testing in enzyme-reactions. Many amino-substituted cyclitols are known to be highly effective glycosidase-inhibitors. The most prominent example is valienamine, but there are many other examples of branched and unbranched cyclitols with a amino-group in different positions. The synthesis of 7-amino valiol gave access to a new class of amino-substituted, branched cyclitols, which also may have potential as a glycosidase-inhibitor. In the de-novo-synthesis starting from p-benzoquinone an independant synthesis of the cyclohexenone system, that results from the Ferrier reaction, could be carried out. The advantage of this method is that all the products synthesized via pathways starting from p-benzoquinone, can be obtained in both enantiomers, using a powerful enzymatic resolution with Pig Pancreas Lipase.