An E-Z boron swivel Compounds with carbon-carbon double bonds can form two distinct isomers, depending on whether the heaviest substituents both carbons lie same side (labeled Z) or diagonally across from each other E). Molloy et al. present a convenient method to reorient that bear and carbonyl substituents. When they are opposed, stay in plane, bond is easily swiveled by photosensitization. However, once as carbonyl, rotates out of plane further sensitization inhibited. Science this issue p. 302

Privileged chiral catalysts-those that share common structural features and are enantioselective across a range of reactions-continue to transform the chemical-research landscape1. In recent years, new reactivity modes have been achieved through excited-state catalysis, processes activated by light, but it is unclear if selectivity ground-state privileged catalysts can be matched. Although interception photogenerated intermediates cycles has partially addressed this challenge2, single,...

A bioinspired, intermolecular radical Stetter reaction of α-keto acids and aldehydes is disclosed that contingent on a formal "radical umpolung" concept. Enabled by secondary amine activation, electrostatic recognition ensures the α-ketocarboxylic acids, which function as latent acyl radicals, are proximal to in situ generated iminium salts. This photoactive contact ion pair an electron donor-acceptor (EDA) complex, undergoes facile single transfer (SET) rapid decarboxylation prior...

An operationally simple protocol is disclosed to facilitate entry benzo-3,4-coumarins directly from biaryl carboxylic acids without the need for substrate prefunctionalization. Complementary classic lactonization strategies, this disconnection relies on oxidation competence of photoactivated (−)-riboflavin (vitamin B2) generate heterocyclic core via photoinduced single electron transfer. Collectively, inexpensive nature catalyst, ease execution, and absence external metal additives are a...

Abstract Strategien zur raumzeitlichen Steuerung von Alkenen durch einen äußeren Reiz sind angesichts der Allgegenwart Rohstoff‐Olefinen in Chemie und ihren Folgeanwendungen notwendig. Angelehnt an den 1‐0‐Schalter, Sehzyklus Säugetieren eine selektive geometrische Isomerisierung Retinal ermöglicht, werden geometrischen positionellen Manipulation des zweidimensionalen Raums mittels chemischer, thermischer lichtinduzierter Prozesse intensiv untersucht. Dieser Kurzaufsatz beleuchtet aktuellen...

A new, three-step, telescoped reaction sequence for the regioselective conversion of N-tosyl hydrazones and aziridines to 3,6-disubstituted 3,5,6-trisubstituted 1,2,4-triazines is described. The process involves an efficient nucleophilic ring opening aziridine, giving access a wide range aminohydrazones, isolated with excellent yields. "one-pot" procedure, combining cyclization oxidation step, allows preparation diversified triazines in good

ConspectusEnantioselective catalysts that exhibit broad generality are disruptive innovators in contemporary synthesis and considered to be "privileged" on account of their expansive reactivity/selectivity profiles. Operating the ground state, these species simultaneously regulate reactivity orchestrate translation chiral information with exquisite efficiency: achieving parity higher-energy (excited-state) scenarios remains a frontier catalysis. Advancing this field will require new...

Abstract Eine bioinspirierte, intermolekulare radikalische Stetter‐Reaktion von α‐Keto‐Säuren und Aldehyden wird beschrieben, die auf dem Konzept einer formalen “radikalischen Umpolung” basiert. Räumliche Nähe α‐Ketocarbonsäuren, als latente Acyl‐Radikale, zum in situ generierten Iminium‐Ion durch elektrostatische Erkennung gewährleistet. Die gebildeten photoaktiven Kontaktionenpaare erweisen sich Elektronen‐Donor‐Akzeptor‐Komplexe, leicht einen Ein‐Elektronen‐Transfer eingehen, gefolgt...

Operating photoswitchable molecules repetitively and reliably is crucial for most of their applications, in particular (opto)electronic devices, related to reversibility fatigue resistance, which both critically depend on the photoisomerization mechanism defined by substitution pattern. Two diarylethene photoswitches bearing biacetyl triplet sensitizers either at periphery or core were investigated using stationary as well transient UV/Vis absorption spectroscopy ranging from femtosecond...

Enantioselective platforms to facilitate prenylation are potentially expansive for translational research due the importance of this motif as a key regulatory biological function. Motivated by conspicuous dearth methods generate chiral prenyl fragments contemporary drug discovery, light-enabled deconjugative isomerization activated alkenes containing an aryl ketone antenna is disclosed through sequential geometric isomerization/hydrogen atom transfer (HAT)/protonation. Detailed mechanistic...

A first-of-its-kind enantioselective aromatic Finkelstein reaction is disclosed for the remote desymmetrization of diarylmethanes. The operates through a copper-catalyzed C-I bond-forming event, and high levels enantioselectivity are achieved deployment tailored guanidinylated peptide ligand. Strategic use transition-metal-mediated reactions enables chemoselective modification aryl iodide products; thus, synthesis diverse set otherwise difficult-to-access diarylmethanes with excellent...

Privileged chiral catalysts continue to transform the reactivity landscape, but achieving parity in excited state paradigms remains a frontier contemporary synthesis. Whilst interception of photogenerated intermediates by ground cycles has partially addressed this challenge, single, photocatalysts that simultaneously regulate and selectivity remain conspicuously scarce. Existing strategies leverage precision donor-acceptor recognition motifs orchestrate enantioinduction. Expanding latitude...

Chiral catalysts that can engage multiple substrates, via distinct activation modes, to deliver enantioenriched products with high levels of fidelity are often described as “privileged”. Antipodal enzymatic specificity, this generality enables the reactivity - selectivity divide in ground state landscapes be effectively reconciled. Achieving latitude excited paradigms remains a frontier, and efforts identify privileged chiral photocatalysts currently core area research. Aluminum salen...

A first-of-its-kind enantioselective aromatic Finkelstein reaction is disclosed for the remote desymmetrization of diarylmethanes. The operates through a copper-catalyzed C‒I bond forming event and high levels enantioselectivity are achieved deployment tailored guanidinylated peptide ligand. Strategic use transition-metal mediated reactions enabled chemoselective modification aryl iodide, thus, synthesis diverse set otherwise difficult-to-access diarylmethanes in excellent selectivity...

The mammalian visual cycle epitomizes the importance of complex polyenes in biology. However, isomerization-based strategies to enable sterodivergent construction these important biomolecules from geometrically defined alkene linchpins remain conspicuously underdeveloped. Mitigating thermodynamic constraints inherent isomerization is further frustrated by considerations atom efficiency idealized low molecular precursors. Herein, we report a general ambiphilic C3 scaffold that can be...

Eine bioinspirierte radikalische Stetter-Reaktion von α-Ketosäuren und Aldehyden wurde entwickelt, die auf einer formalen “radikalischen Umpolung” basiert. R. Gilmour et al. kombinieren in der Zuschrift S. 1221 Aktivierungsprinzipien aus Organo- Photokatalyse, um den Anwendungsbereich klassischen α,β-ungesättigte Aldehyde als Akzeptoren zu erweitern so ein lange bestehendes Chemoselektivitätsproblem lösen.