63 research outputs found
Total synthesis and structural assignment of (−)-fusaequisin A
(−)-Fusaequisin A is an irregularly assembled polyketide isolated from the ascomycete Fusarium equiseti. Fusaequisin A shares a carbon backbone with curvicollide C from the ascomycete Podospora curvicolla but its absolute configuration remained hitherto unsettled. Herein, we document the total synthesis of (−)-fusaequisin A and its 4-O-desmethyl derivative following a central-to-lateral building block strategy. Catalytic asymmetric Claisen rearrangement, Julia-Kocienski olefination and olefin cross-metathesis served as key C/C-connecting transformations. The constitution and absolute configuration of (−)-fusaequisin A was deduced and the original structural assignment was adjusted
An update on cyclohepta[b]indoles
The cyclohepta[b]indole scaffold constitutes a salient structural motif in natural products as well as in men-made pharmaceutically active ingredients. Cyclohepta[b]indoles consist of an indole nucleus fused to a seven-membered carbacycle. Interest in cyclohepta[b]indole chemistry originates from natural product chemistry and medicinal chemistry. The chemistry of cyclohepta[b]indole-based organic functional materials may be a research area with some potential. The state of the art of cyclohepta[b]indoloid chemism has been comprehensively and scholarly summarized by the leading review article of Stempel and Gaich in 2016. Following this lead, our Minireview covers the literature from 2016 to 2021
Triphenyl(prop-2-yn-1-yl)silane
In the title compound, C21H18Si, the coordination geometry around the Si atom is a slightly distorted tetrahedron with C—Si—C angles in the range 106.05 (11) to 110.58 (10) ° and Si–C bond lengths in the range 1.855 (2) to 1.883 (3) Å. The alkyne C—C bond length is 1.167 (4) Å. The dihedral angles between the three phenyl rings are 63.89 (7), 86.38 (7) and 70.51 (8)°. In the crystal, molecules interact only by van der Waals forces
(2SR,3SR)-Isopropyl 3-{[dimethyl(phenyl)silyl]methyl}-2-hydroxy-2-vinylpent-4-enoate
The relative configuration of the title compound, C19H28O3Si, which was synthesized using a dienolate-[2,3]-Wittig rearrangement, was corroborated by single-crystal X-ray diffraction analysis. The Si—C bond distances are in the range 1.858 (2)–1.880 (2) Å and an intramolecular O—H⋯O hydrogen bond helps to stabilize the molecular conformation
(3R,4R,5S)-4-Hydroxy-3-methyl-5-[(2S,3R)-3-methylpent-4-en-2-yl]-4,5-dihydrofuran-2(3H)-one
The relative configuration of the title compound, C11H18O3, which was synthesized using a catalytic asymmetric Gosteli–Claisen rearrangement, a diastereoselective reduction with K-Selectride and an Evans aldol addition, was corroborated by single-crystal X-ray diffraction analysis. The five-membered ring has an envelope conformation with a dihedral angle of 29.46 (16)° between the coplanar part and the flap (the hydroxy-bearing ring C atom). In the crystal, molecules are connected via bifurcated O—H⋯(O,O) hydrogen bonds, generating [010] chains
(3S,4S,5R)-4-Hydroxy-3-methyl-5-[(2S,3R)-3-methylpent-4-en-2-yl]-4,5-dihydrofuran-2(3H)-one
The relative configuration of the title compound, C11H18O3, was corroborated by single-crystal X-ray diffraction analysis. In the crystal, molecules are linked via a O—H⋯O hydrogen bond and a chain of molecules is formed along [010]
Datengenerierung in Automationsgeräten, Datenintegration und Visualisierung in CPS-Leitständen
Der durchgängige Einsatz von ETHERNET-Technologien in der Industrie ermöglicht den Durchgriff auf Daten von der (Werks-)Leitebene bis in die Feldebene (Aktoren und Sensoren). Die Realisierung dieser Funktionen bedarf struktureller und funktioneller Festlegungen und Normative, an die Entwickler und Nutzer zu binden sind. Die konzipierten und umgesetzten Daten-Erfassungs-, -Übertragungs- und -Visualisierungskonzepte konnten in ihrer Funktionsfähigkeit demonstratorhaft nachgewiesen werden. Eine Anpassung auf weitere Technologien ist möglich und im Zuge der Weiterentwicklung in Richtung Vermarktbarkeit vorgesehen
(±)-syn-Isopropyl 4-(1,1,1,3,3,3-hexafluoropropan-2-yloxy)-1-hydroxy-3-methyl-2-(prop-1-ynyl)cyclopent-2-enecarboxylate
The title compound, C16H18F6O4, was obtained through an unprecedented one-pot reaction sequence involving a Gosteli–Claisen rearrangement and a cycloisomerization. The constitution and relative configuration were determined by single-crystal X-ray diffraction analysis. In the crystal, molecules are connected via O—H ⋯ O hydrogen bonds
Photochemical approach to the cyclohepta[b]indole scaffold by annulative two-carbon ring-expansion
We report on the implementation of the concept of a photochemically elicited two-carbon homologation of a π-donor–π-acceptor substituted chromophore by triple-bond insertion. Implementing a phenyl connector between the slide-in module and the chromophore enabled the synthesis of cylohepta[b]indole-type building blocks by a metal-free annulative one-pot two-carbon ring expansion of the five-membered chromophore. Post-irradiative structural elaboration provided founding members of the indolo[2,3-d]tropone family of compounds. Control experiments in combination with computational chemistry on this multibond reorganization process founded the basis for a mechanistic hypothesis
(4R)-4-Benzyl-3-{(4S)-4-chloro-4-[(S)-2,2-dimethyl-1,3-dioxolan-4-yl]butanoyl}-1,3-oxazolidin-2-one
The title compound, C19H24ClNO5, was synthesized and subsequently employed in an Evans alkylation. The purpose was to prove the absolute configuration in the projected synthesis of the side chain of (–)-Lytophilippine A. The oxazolidinone and the isopropylidene acetal rings have twisted conformations. The oxazolidinone and side-chain carbonyl groups are orientated in an antiperiplanar arrangement to minimize van der Waals repulsions. Furthermore, the Cl atom and the acetonide-protected secondary alcohol are also in an antiperiplanar arrangement with a torsion angle of 173.64 (14)°. The absolute configuration was determined and agrees with the configuration of the used chiral auxiliary
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