Catnip craze: Nepetalactone, the psychoactive ingredient of catmint, was selected as starting material for the first enantioselective synthesis of englerin A. This cytotoxic guaiane sesquiterpene is a highly selective inhibitor (1–87 nM) of several renal cancer cell lines. The absolute configuration of this natural product was determined by total synthesis.
A method for generating (E)-α,β-unsaturated aldehydes from Z-allylic alcohols or E/Z-mixtures is described. The one-pot procedure involves a Cu-catalyzed oxidation followed by an organocatalytic Z/E-isomerization with N,N-dimethylaminopyridine (DMAP).
The intramolecular Rauhut-Currier reaction creates a carbon-carbon bond between two tethered Michael acceptors. Previous asymmetric versions have relied on 1,4-additions of chiral nucleophilic catalysts. Herein, we investigate a novel strategy that involves the formation of electron rich dienamines as key intermediates. Our methodology provides an efficient entry to the iridoid framework.
Von Katzenminze und Nierenkrebs: Nepetalacton, der psychoaktive Wirkstoff der Katzenminze ist das Ausgangsmaterial für die Totalsynthese eines cytotoxischen Naturstoffs. Das Guaian‐Sesquiterpen Englerin A ist ein selektiver Inhibitor (1–87 nM) mehrerer Nierenkrebs‐Zelllinien. Durch die vorgestellte Totalsynthese wurde die bislang unbekannte absolute Konfiguration aufgeklärt.
Both the racemic and the stereoselective synthesis of the silicon‐modified amino acid p‐(tBu2FSi)C6H4CH2(NH2)COOH (SiFA‐phenylalanine, 6) and its derivatives p‐(tBu2FSi)C6H4CH2(NHBoc)COOH (10) and p‐(tBu2FSi)C6H4CH2(NHFmoc)COOH (11) are reported. The latter two compounds are valuable building blocks for the convenient introduction of silicon‐based fluoride acceptors (SiFAs) into peptides by solid‐phase peptide syntheses (SPPS). As prove of principle, the Tyr3‐octreotate derivatives 12, 13 and 14 were prepared by using standard protocols of the solid‐phase peptide synthesis (SPPS). They were labelled with 18F‐fluorine by isotopic exchange in radiochemical yields of up to 70 % (with radiochemical purity ranging between 92 and 99 %). The incorporation of 18F‐fluorine into the SiFA‐modified amino acid 6 was studied as the latter may also serve as a tracer in PET. After purification, [18F]‐6 showed a remarkable stability in an isotonic solution. Also reported is the molecular structure, as determined by single‐crystal X‐ray diffraction analysis, of p‐(tBu2FSi)C6H4CHCH[C(O)OMe]NHC(O)OCH2Ph (8), which serves as a precursor for the stereoselective synthesis of compound 6.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.