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The upcycling of waste biomass into valuable materials by resource‐efficient chemical transformations is a prime objective for sustainable chemistry. This approach is demonstrated in a straightforward light‐driven synthesis of polyols and polyurethane foams from the multi‐ton waste products of cashew nut processing. The photo‐oxygenation of cardanol from nutshell oil results in the formation of synthetically versatile hydroperoxides. The choice of the workup method (i. e. reduction, hydrogenation, epoxidation) enables access to a diverse range of alcohols with tunable alkene and OH functions. Condensation with isocyanates to give rigid polyurethane foams provides a resource‐efficient waste‐to‐value chain that benefits from the availability of cardanol and installation of OH groups from aerial O2. [ABSTRACT FROM AUTHOR]

A flexible and efficient synthesis of the potent human topoisomerase inhibitor (5 Z,9 Z)-eicosa-5,9-dienoic acid was explored; the presented method represents a generally applicable approach towards demospongic acids and related natural products. Key steps of the synthesis involve chemoselective hydroboration, Corey-Fuchs alkynylation, Z-selective Lindlar reduction, tetrapropylammonium perruthenate catalyzed direct oxidation of a primary alcohol to the corresponding acid, and Arndt-Eistert homologation. Thus, the total synthesis of (5 Z,9 Z)-eicosa-5,9-dienoic acid was achieved in 10 steps in an overall yield of 20 %. [ABSTRACT FROM AUTHOR]

The ruthenium tetroxide catalyzed direct oxidative cyclization is a powerful synthetic method for the diastereoselective preparation of THF diols from simple achiral 1,5-diene starting materials with significant relevance to target-oriented and natural product synthesis. We here report that an aged precatalyst solution exhibits an extraordinarily high reactivity. Thus, even at 50 ppm catalyst loading, impressive results were achieved with good to high yields and excellent diastereoselectivities for the four stereogenic centers that were established in this single-step transformation. Turnover numbers of up to 15 000 and turnover frequencies of up to 3660 h−1 were obtained. The ageing effect was analyzed spectroscopically and a preliminary hypothesis to explain the reactivity is given. Finally, the generality of this effect in oxidative cyclization chemistry was demonstrated by using a set of substrates with different substitution patterns and different geometries of the reacting double bonds. [ABSTRACT FROM AUTHOR]

Eine regio ‐ und stereoselektive inverse Prenylierung von Indol ‐ und Tryptophan ‐ Derivaten wird präsentiert. Alle vier möglichen Stereoisomere sind durch diese Iridium ‐ katalysierte Reaktion zugänglich. Die Stereoselektivität wird durch eine Kombination aus chiralem Phosphoramidit ‐ Liganden mit einem achiralen Boran ‐ Additiv gesteuert und kann abhängig von der Art des Borans vollständig umgekehrt werden. Es genügt somit nur ein Enantiomer des Liganden, um alle denkbaren Stereoisomere herzustellen. Das synthetische Potential der Methode wurde in einer kurzen Synthese von Amauromin und seinen zwei natürlichen Diastereomeren demonstriert. Asymmetrische Prenylierung: Eine regio ‐ und stereoselektive inverse Prenylierung von Indol ‐ und Tryptophan ‐ Derivaten wird präsentiert. Alle vier möglichen Stereoisomere sind durch diese Iridium ‐ katalysierte Reaktion zugänglich. Die Stereoselektivität wird durch eine Kombination aus chiralem Phosphoramidit ‐ Liganden und achiralem Boran ‐ Additiv gesteuert und kann abhängig von der Art des Borans vollständig umgekehrt werden. [ABSTRACT FROM AUTHOR]

A regio- and stereoselective reverse prenylation of indole and tryptophan derivatives is presented. All four possible stereoisomers are accessible through this iridium-catalyzed reaction. The stereoselectivity is controlled by a chiral phosphoramidite ligand in combination with an achiral borane additive and can be switched by changing the nature of the borane. One enantiomer of the ligand is thus sufficient to prepare all possible isomers. The synthetic potential of this method was demonstrated by a short total synthesis of amauromine and its two natural diastereomers. [ABSTRACT FROM AUTHOR]

The stereoselectivity of the reaction is dictated by the combination of an achiral borane additive and one chiral phosphoramidite ligand and can be adjusted by changing the borane. [ABSTRACT FROM AUTHOR]

Review: [141 refs. [ABSTRACT FROM AUTHOR]