The mechanisms of two diterpene cyclases from streptomycetes-one with an unknown product that was identified as the spirocyclic hydrocarbon spiroviolene and one with the known product tsukubadiene-were investigated in detail by isotope labeling experiments. Although the structures of the products were very different, the cyclization mechanisms of both enzymes proceed through the same initial cyclization reactions, before they diverge towards the individual products, which is reflected in the close phylogenetic relationship of the enzymes.

Die Mechanismen von zwei Diterpencyclasen aus Streptomyceten – eine mit unbekanntem Produkt, das als der spirocyclische Kohlenwasserstoff Spiroviolen identifiziert wurde, und eine mit dem bekannten Produkt Tsukubadien – wurden detailliert durch Isotopenmarkierungsexperimente untersucht. Obwohl die Strukturen der Produkte sehr unterschiedlich sind, beginnen die Cyclisierungsmechanismen beider Enzyme mit derselben Cyclisierungsreaktion, bevor sie auf dem Weg zu ihren individuellen Produkten divergieren. Dies spiegelt die nahe phylogenetische Verwandtschaft der Enzyme wider.

No abstract

In this disclosure, we summarize the preliminary metabolic profiling of the PI3Kδ inhibitor CDZ173 (leniolisib, 1a) obtained from incubations of the unlabeled compound and the synthesis of its metabolically stable tritium isotopologue 1b used for metabolite structure confirmation. Access to 1b was achieved when a halogenated precursor was subject to Hal/3H‐exchange. Hence, [3H]CDZ173 with specific activity 630 GBq/mmol, HPLC‐RA 97% and ee = 99.2% was obtained. Synthetic key to the precursor was using a bis‐halo‐pyridine in a Pd‐catalyzed mono‐amination of the tetrahydropyrido‐pyrimidine core. Stereochemistry of the synthetic precursors were confirmed by X‐ray analysis of the unlabeled bis‐halo‐pyridines and chiral HPLC of the tritiated material. The correct position of tritium label in the target, was confirmed by 3H‐NMR difference spectroscopy. Besides, we report on the validation of the radiotracer as a tool for pre‐clinical ADME in incubations with hepatocytes. Based on this data, we present a quantitative metabolite profile of leniolisib which was confirmed by independently synthesized metabolite references. The conformation of CDZ173 was investigated by NMR suggesting two different amide backbones each with specific pyrrolidine puckerings.