Other natural products U 0800 Spirodionic Acid, a Novel Metabolite from Streptomyces sp. Part 1. Structure Elucidation and Diels-Alder-Type Biosynthesis. -(TEXTOR, A.; PAPASTAVROU, I.; SIEWERT, J.; MAGULL, J.; KULIK, A.; FIEDLER, H.-P.; VON ZEZSCHWITZ, P.; GROND*, S.; Chem. Eur.

Cyclohexane derivatives Q 0040Rhodium-Catalyzed Enantioselective 1,2-Addition of Aluminum Organyl Compounds to Cyclic Enones. -Organo-aluminum compounds undergo 1,2-additions to cyclic enones that lack substituents in the α-position. The method is also used for 1,2-arylation with further oxidation to give diastereomerically pure epoxides (XV).-(SIEWERT, J.; SANDMANN, R.; VON ZEZSCHWITZ*, P.; Angew.

Improved Synthesis of Cyclic Tertiary Allylic Alcohols by Asymmetric 1,2-Addition of AlMe 3 to Enones. -The development of an improved protocol for the enantioselective Rh(I)/BINAP-catalyzed 1,2-addition of trimethylaluminum to cyclic enones is reported. 31 P NMR analysis of the reaction reveals that the catalyst in its resting state is a chloride-bridged dimer. This insight leads to the use of silver tetrafluoroborate as an additive for in situ activation of the dimeric precatalyst. Various 5-7-membered cyclic enones can be transformed into tertiary allylic alcohols with excellent levels of enantioselectivity. -(KOLB, A.; ZUO, W.; SIEWERT, J.; HARMS, K.; VON ZEZSCHWITZ*, P.; Chem. -Eur.

First Tandem Asymmetric Conjugate Addition of Alkenyl Nucleophiles and Silyl Trapping of the Intermediate Enolates. -The asymmetric Rh-catalyzed addition of alkenylzirconocenes is described. High enantioselectivities are obtained even with the challenging cyclopentenone as a substrate. -(WESTMEIER, J.; PFAFF, C.; SIEWERT, J.; VON ZEZSCHWITZ*, P.; Adv. Synth. Catal. 355 (2013) 13, 2651-2658, http://dx.

Other natural products U 0800 Spirodionic Acid, a Novel Metabolite from Streptomyces sp. Part 2. Total Synthesis Through a Twofold Michael Addition as a Selective Spiroanellation Strategy. -(SIEWERT, J.; TEXTOR, A.; GROND, S.; VON ZEZSCHWITZ*, P.; Chem. Eur.