Unsaturated O- and N-heterocycles from carbohydrate feedstocks.

With reference to the impending transition of chemical industry from depleting fossil raw materials to renewable feedstocks--the end of cheap oil is predicted for 2040 at the latest--this account gives an overview on chemically transforming carbohydrates, by far the major part of the annually regrowing biomass, into the following unsaturated O- and N-heterocycles with versatile industrial application profiles: furans, pyrans, dihydropyranones, pyrroles, pyrazoles, imidazoles, pyridinols, pyrazines, and quinoxalines. Although the emphasis was laid on conversions that can be effected in practical one-pot procedures or in a few large-scale-adaptable steps, a broad structural variety of products emerges that have not only diverse chemical functionalities but also hydrophilic "residual sugar" portions that render them water-soluble and readily biodegradable.