An impressive number of chemo-catalyzed cascade-reactions (especially those involving cyclizations) have been accomplished by using palladium [1-3]. Other types of typical cascade-reactions (although they have been denoted as 'tandem-reactions' in the respective publications) have been reviewed and classified according to their type of mechanism [4]. All of these reaction sequences were initiated by an organic or inorganic catalyst, or by thermal reactions. On the contrary, only few examples of cascade-reactions have been reported, where the initiation of the reaction cascade consisted of a biotransformation [5]. Taking advantage of the unparalleled diastereo- and enantio-specificity of enzymes, in many cases the reaction cascade was turned into an asymmetric fashion which furnished non-racemic product(s).

An efficient five-step synthesis of the pyrido[2,3,4-kl]acridin-8-one system is described, using a Suzuki coupling of a 4-iodoquinoline and a oxidative demethylation with cobalt trifluoride as the key steps.

Integration of parallel chromatography on both, gel permeation and silica gel chromatography by making use of the CombiFlashTM si1000s system (ISCO, Lincoln, USA) into purification process to speed up the isolation of secodary metabolites from microorganisms. As an example, we applied this approach to Streptomyces sp. (GT 061089) which led to the isolation and structural characterization of six 2-3-disubstituted butanoids (1 to 6), four 2,4-disubtituted butanoids (7 to 10), a monoterpenoid (11), two indol compounds (12, 13), a furan-3-carboxylic acid (14), as well as two already known isocoumarins (15, 16). The isolated pure compounds were characterized by spectroscopic methods and chemical transformations. The results of biological tests showed that both 15 and 16 possess medium cytotoxic activity and strong inhibiting activity on horse radish peroxidase. 15 also exhibits antiviral activity as well as a distinct inhibiting activity on 3a-hydroxysteroid dehydrogenase (3a-HSD).

Nor- and bisnorsesquiterpenoids 1 and 2 have been synthesized starting from (S)-(+)-Wieland-Miescher ketone analogue 4 via solid state Baeyer-Villiger reaction as a key step.

Tryprostatin B and its analogue containing alanine instead of proline were synthesized from cyclo-(L-Trp-L-Pro) and cyclo-(L-Trp-L-Ala), respectively, by tandem C-3 prenylation/cyclization, followed by acid-catalyzed migration of the prenyl group to the indole C2 position.

Epothilones A and B I (Fig. 1) are naturally occurring 16-membered macrolides, which are produced by the myxobacterium Sorangium cellulosum. [1] Although these compounds do not share any obvious structural similarities with the prominent anticancer drug paclitaxel (Taxol), they exhibit a similar biological profile in vitro, including the ability to inhibit microtubule depolymerization and to induce apoptosis in human cancer cell lines with sub-nM IC50s. [2] [3] Epothilone B is a 3-20-fold more potent inhibitor of human cancer cell growth than paclitaxel and unlike paclitaxel is also effective against multidrug-resistant cell lines. Epothilone B has demonstrated potent in vivo antitumor activity [3] in and is currently undergoing Phase I clinical trials by Novartis.

Seven-membered lactones which possess alkyl or substituted alkyl groups in different positions are interesting pheromone precursors.[1] Such a compound is (-)-lardolure (1), the aggregation pheromone of the acarid mite, Lardoglyphus konoi,[2] which was prepared in a thirteen-step synthesis starting from the racemic lactone 2 by Mori et al.[3] The resolution of the hydroxycarboxylic acids (+)-5 and (–)-5 via the diastereomeric precursors 4a and 4b was the key reaction of this synthesis (scheme 1). The enzymatic Baeyer-Villiger oxidation of the ketone 6 (scheme 2) and the kinetic resolution of the racemic lactone 2 with an esterase (scheme 3) could be alternative ways for a shorter synthesis of the hydroxyacids (+)-5 and (–)-5, respectively.

The effective and selective molecular recognition of amino acids in water is still a challenge in supramolecular chemistry. Because of the frequent use of the side chains of basic amino acids (Lys, Arg, His) for biological processes the molecular recognition of these amino acids by synthetic receptor molecules is of special interest [1]. Recently we presented a new macrocyclic receptor molecule, which binds arginine and lysine in a stereoselective fashion (Fig. 1) [2]. The mechanism of enantioselective recognition relies on two simultaneous cation-phosphonate interactions � i. e. binding of a specific cationic group of the amino acid to a specific phosphonate moiety in the receptor molecule. After docking the amino acid comes into van der Waals-contact of the chiral surface of the chiral bridging unit in 1 and one enantiomer is bound preferentially.

In contrast to the multitude of different binding motifs for the molecular recognition of ammonium cations very few efficient guanidinium receptors have been reported and even less amidinium hosts [1]. The latter is surprising in view of important role of the amidinium functionality in drugs targeting binding pockets for the arginine sidechain etc. The challenge, however, is quite clear: One has to surround the amidinium group in a halfmoon-like array with at least four hydrogen bond acceptors, which are ideally preoriented for maximum electrostatic as well as hydrogen bond interactions.

Condensation of chlorides of substituted pyrazine-2-carboxylic acids with ring substituted anilines yielded a series of anilides of 6-chloropyrazine-2-carboxylic, 5-(1,1-dimethylethyl)-pyrazine-2-carboxylic or 6-chloro-5-(1,1-dimethylethyl)pyrazine-2-carboxylic acids. Products were tested for their photosynthesis-inhibiting activity. The most active inhibitor of oxygen evolution rate in spinach chloroplasts was 3,5-bis(trifluoromethyl)anilide of 6-chloropyrazine-2-carboxylic acid (IC50 = 0.026 mmol dm-3), the most active antialgal compound was 3-methylanilide of 6-chloro-5-(1,1dimethylethyl)pyrazine-2-carboxylic acid (IC50 = 0.063 mmol dm-3). The elimination of phenolic group in the benzene moiety led to an decreased photosynthesis-inhibitory activity.