We report a novel approach to the classical natural product quinine that is based on two stereoselective key steps, namely a C−H activation and an aldol reaction, to unite the two heterocyclic moieties of the target molecule. This straightforward and flexible strategy enables a concise synthesis of natural (−)‐quinine, the first synthesis of unnatural (+)‐quinine, and also provides access to unprecedented C3‐aryl analogues, which were prepared in only six steps. We additionally demonstrate that these structural analogues exhibit improved antimalarial activity compared with (−)‐quinine both in vitro and in mice infected with Plasmodium berghei.
Despite recent proliferation of programmable robotic chemistry hardware, current chemical programming ontologies lack essential structured programming constructs like variables, functions, and loops. Herein we present an integration of these concepts into χDL, a universal high-level chemical programming language executable in the Chemputer. To achieve this, we introduce reaction blueprints as a chemical analog to functions in computer science, allowing to apply sets of synthesis operations to different reagents and conditions. We further expand χDL with logical operation queues and iteration via pattern matching. The combination of these new features allows encoding of chemical syntheses in generalized, reproducible, and parallelized digital workflows rather than opaque and entangled single-step operations. This is showcased by synthesizing chiral diarylprolinol catalysts and subsequently utilizing them in various synthetic transformations (13 separate automated runs affording 3 organocatalysts and 12 distinct enantioenriched products in 42–97% yield, up to > 99:1 er), including automated catalyst recycling and reuse.
The metal‐promoted nucleophilic addition of sulfur ylides to π‐systems is a well‐established reactivity. However, the driving force of such transformations, elimination of a sulfide moiety, entails stoichiometric byproducts making them unfavorable in terms of atom economy. In this work, a new take on sulfur ylide chemistry is reported, an atom‐economical gold(I)‐catalyzed synthesis of dihydrobenzo[b]thiepines. The reaction proceeds under mild conditions at room temperature.
Wir berichten über einen neuen Ansatz zum klassischen Naturprodukt Chinin, der auf zwei stereoselektiven Schlüsselschritten, nämlich einer C(sp3)‐H‐Aktivierung und einer Aldol‐Reaktion, welche die beiden heterocyclischen Fragmente des Zielmoleküls vereinigt, basiert. Diese direkte und flexible Strategie ermöglicht eine kurze Synthese von natürlichem (−)‐Chinin und die erste Synthese von nichtnatürlichem (+)‐Chinin, und sie bietet Zugang zu bisher unbekannten C3‐Aryl‐Analoga, welche in nur 6 Stufen hergestellt werden können. Des Weiteren zeigen wir, dass diese strukturellen Analoga, im Vergleich zu (−)‐Chinin, eine erhöhte Anti‐Malaria‐Aktivität sowohl in vitro als auch in vivo, an mit Plasmodium berghei infizierten Mäusen, aufweisen.
Efficient optimization procedures in chiral catalysis are usually linked to a straightforward strategy to access groups of structurally similar catalysts required for fine-tuning. The ease of building up such ligand libraries can be increased when the structure-modifying step (introduction of a substituent) is done at a later stage of the synthesis. This is demonstrated for the extended family of di- and tetranaphtho azepinium compounds, widely used as chiral phase transfer catalysts (PTC). Using 2,6-diiodo-4,5-dihydro-3H-dinaphtho[2,1-c:1′,2′-e]azepine and 4,8-diiodo-6,7-dihydro-5H-dibenzo[c,e]azepine, respectively, as key intermediates, 18 spiro-azepinium compounds were synthesized in a total yield of 25–42% over 6–7 steps from 1,1′-binaphthyl-2,2′-dicarboxylic acid or diphenic acid, respectively. The replacement of iodo groups with aryl substituents was performed as the last or the penultimate step of the synthesis.