Positionelle und geometrische Isomerisierung von Alkenen: der Gipfel der Atomökonomie

Angewandte Chemie, Journal Year: 2019, Volume and Issue: 131(39), P. 13789 - 13800

Published: June 25, 2019

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 Stand Forschung Aktivierung dem Ermöglichen Direktionalität diesen fundamentalen chemischen Transformationen.

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Catalytic Enantioselective Synthesis of Difluorinated Alkyl Bromides

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(35), P. 14831 - 14837

Published: Aug. 17, 2020

We report an iodoarene-catalyzed enantioselective synthesis of β,β-difluoroalkyl bromide building blocks. The transformation involves oxidative rearrangement α-bromostyrenes, utilizing HF–pyridine as the fluoride source and m-CPBA stoichiometric oxidant. A catalyst decomposition pathway was identified, which, in tandem with structure–activity relationship studies, facilitated development improved providing higher enantioselectivity lower loadings. versatility difluoroalkyl products demonstrated via highly enantiospecific substitution reactions suitably reactive nucleophiles. origins were investigated using computed interaction energies simplified substrate structures, evidence for both CH−π π–π transition state interactions critical features.

Language: Английский

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Polar Organofluorine Substituents: Multivicinal Fluorines on Alkyl Chains and Alicyclic Rings

Chemistry - A European Journal, Journal Year: 2020, Volume and Issue: 26(36), P. 7981 - 7997

Published: Feb. 21, 2020

This Review outlines the progression, primarily of our own work, but with important contributions from other labs, on synthesis and properties multiple vicinally fluorinated alkyl chains rings. Chain conformations individual diastereoisomers -CHF- at adjacent carbons are influenced by stereoelectronic factors associated polar C-F bond polarised geminal hydrogens. Generally, chain will prefer a conformation which acts to minimise overall molecular polarity, where bonds orient away each other. However, when vicinal fluorine atoms positioned ring then more constrained. The adopt optimal such as chair in cyclohexane can be introduced stereochemistry that forces parallel (axial) orientations. In case cyclohexane, 1,3-diaxial arrangements impart considerable polarity ring, resulting an electronegative 'fluorine face' electropositive 'hydrogen face'. For all-syn 1,2,3,4,5,6-hexafluorocyclohexane, this arrangement generates unusually aliphatic system. Most recently concept has been extended preparation 1,2,3-trifluorocyclopropanes, rigid system one face hydrogens Lipophilicity Log P values compounds indicate they significantly than their parent alicyclic hydrocarbons give some positive indication for future role substituents medicinal chemistry. Expanding require access improved methods these motifs consequently broader range building blocks, however exciting new have emerged briefly reviewed.

Language: Английский

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Catalytic Vicinal Dichlorination of Unactivated Alkenes

ACS Catalysis, Journal Year: 2019, Volume and Issue: 9(8), P. 7232 - 7237

Published: July 8, 2019

Organocatalytic strategies for the programmed, catalytic oxidation of π-bonds through regioselective halogenation remain comparatively underdeveloped. The vicinal dichlorination unactivated alkenes is a pertinent example, where stoichiometric reagents and prefunctionalization steps are often employed. This surprising given prominence 1,2-dichloro moiety in an array bioactive natural products both terrestrial marine origin. Inspired by Willgerodt's seminal discovery 1886 that PhICl2 can be generated passing Cl2(g) iodobenzene, has been designed on basis I(I)/I(III) manifold. In situ generation p-TolICl2 achieved using Selectfluor CsCl. Substrate scope, mechanistic delineation, preliminary validation enantiomeric variant established. Over century after initial Willgerodt reagent (PhICl2), operationally simple, alternative validated.

Language: Английский

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Enantio‐ and Diastereoselective, Complete Hydrogenation of Benzofurans by Cascade Catalysis

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(24), P. 13677 - 13681

Published: April 12, 2021

We report an enantio- and diastereoselective, complete hydrogenation of multiply substituted benzofurans in a one-pot cascade catalysis. The developed protocol facilitates the controlled installation up to six new defined stereocenters produces architecturally complex octahydrobenzofurans, prevalent many bioactive molecules. A unique match chiral homogeneous ruthenium-N-heterocyclic carbene situ activated rhodium catalyst from precursor act sequence enable presented process.

Language: Английский

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