While the methodic arsenal of organic synthesis using fossil carbon resources has been highly developed over the last 100 years, there is a considerable lack of synthetic routes being in accordance with the rules of sustainable chemistry for the efficient transformation of complex and highly functionalized bulk natural products into fine chemicals or functionalized materials. Our target compounds are value chemicals, which are obtained by selective catalytic transformation of abundant carbohydrates. We develop selective chemical photocatalysts for endothermic or kinetically hindered organic reactions . This will pave the way to a broader use of solar energy for chemical transformations. Catalyses involving one electron transfer processes, such as radical cyclizations, or two electron transfer processes, e.g. two coupled redox transformations, are investigated. Whenever possible, the visible part of the solar light spectrum is used as energy source.