Flexible synthesis of polyfunctionalised 3-fluoropyrroles

An efficient and selective approach for the synthesis of polyfunctionalised 3-fluoropyrroles has been developed starting from commercial aldehydes. The methodology is concise, efficient and allows for the modular and systematic assembly of polysubstituted 3-fluoropyrroles. This synthesis provides an alternative and highly convergent strategy for the generation of these chemically and biologically important units

Reactivity of (1-methoxycarbonylpentadienyl)iron(1+) cations with hydride, methyl, and nitrogen nucleophiles

The reaction of tricarbonyl and (dicarbonyl)triphenylphosphine (1-methoxycarbonyl-pentadientyl)iron(1+) cations 7 and 8 with methyl lithium, NaBH3CN, or potassium phthalimide affords (pentenediyl)iron complexes 9a-c and 11a-b, while reaction with dimethylcuprate, gave (E,Z-diene)iron complexes 10 and 12. Oxidatively induced-reductive elimination of 9a-c gave vinylcyclopropanecarboxylates 17a-c. The optically active vinylcyclopropane (+)-17a, prepared from (1S)-7, undergoes olefin cross-metathesis with excess (+)-18 to yield (+)-19, a C9C16 synthon for the antifungal agent ambruticin. Alternatively reaction of 7 with methanesulfonamide or trimethylsilylazide gave (E,E-diene)iron complexes 14d and e. Huisgen [3 + 2] cyclization of the (azidodienyl)iron complex 14e with alkynes afforded triazoles 25a-e

X-ray Crystal Structures and the Facile Oxidative (Au−C) Cleavage of the Dimethylaurate(I) and Tetramethylaurate(III) Homologues

Dimethylaurate(I) has been prepared as the crystalline tetrabutylammonium salt for comparison with the known tetramethylaurate(III) analogue. The linear structure of dimethylaurate(I) and the square-planar structure of tetramethylaurate(III) have both been confirmed by X-ray crystallography. One-electron oxidation of dimethylaurate(I) by either ferrocenium or arenediazonium cations produces the metastable dimethylgold(II) intermediate, which can be trapped as the paramagnetic 9,10-phenanthrenequinone (PQ) adduct. Otherwise, dimethylgold(II) is subject to rapid reductive elimination of ethane and affords metallic gold (mirror). The analogous oxidation of tetramethylaurate(III) by ferrocenium, arenediazonium, or nitrosonium cations also proceeds via electron transfer to generate the putative tetramethylgold(IV) intermediate. The highly unstable (CH3)4AuIV spontaneously undergoes homolytic cleavage to produce methyl radical and the coordinately unsaturated trimethylgold(III), which can be intercepted by added triphenylphosphine to afford Me3AuIIIPPh3

Carboranylmethylene-substituted phosphazenes and polymers thereof

Carboranylmethylene-substituted cyclophosphazenes are described which can be thermally polymerized into carboranylmethylene-substituted phosphazene polymers. The polymers are useful as thermally stable coatings. Also, due to the characteristics of these polymers in acting as a ligand for transition metals, metalocarboranylmethylene phosphazene polymers are described which can act as immobilized catalyst systems, and are electrically conductive and superconductive

Zur intramolekularen Wechselwirkung von Cyclopropylidenen mit dem Bicyclo[1.1.0]butansystem

No abstract availabl

Synthese und Eigenschaften von TrimethyIstannylmethyl-Indium(III)-Verbindungen

Trimethyltin methyllithium reacts with InCl3, CH3InCl2 and R2InCl (R = CH3, t-C4H9) with formation of the new compounds In(CH2SnMe3)3, CH3In(CH2SnMe3)2, (CH3)2InCH2SnMe3 and (t-C4H9)2InCH2SnMe3. The compounds are characterized by elemental analyses, 1H, 13C, 119Sn NMR and IR spectra

Regiospezifische Synthese von 2-Phenyl-pyrano[3,4-b]pyranonen (Oxaflavon-Derivaten) mit Tetrahydro-3-pyranon

Tetrahydro-3-pyranon (5) reagiert unter definierten Bedingungen mit Trimethylsilylchlorid regiospezifisch zum Enolether 6. Nach Spaltung mit Methyllithium und Reaktion mit Zimtsäurechlorid entsteht daraus das 4-Cinnamoylpyranon 8. Protonenkatalysierter Ringschluß und DDQ-Dehydrierung liefern die Pyrano[3,4-b]pyranone 9 bzw. 10

Synthesis of indoles via alkylidenation of acyl hydrazides

Indoles have been synthesised via alkylidenation of acyl phenylhydrazides using phosphoranes and the Petasis reagent, followed by in situ thermal rearrangement of the product enehydrazines. The Petasis reagent provides an essentially neutral equivalent of the [acid-catalysed] Fischer indole synthesis, but with acyl phenylhydrazides as starting substrates. Alkylidene triphenylphosphoranes convert aroyl phenylhydrazides to indoles, but acyl phenylhydrazides derived from aliphatic carboxylic acids undergo a Brunner reaction to form indolin-2-ones

Additionsreaktionen an intramolekular basenstabilisierte Ge=N- und Ge=S-Doppelbindungen

The GeN bond of 1 adds hydrogen chloride, ethanol, tert-butyl alcohol, methyllithium, and methyl iodide to form 3-6 and 8. The GeS bond in 2 analogously adds methyl iodide to yield 10. In the resulting products the electropositive part of the polar reactand is bound to nitrogen or sulfur, while the electronegative one is on the germanium atom. In the lithium derivative 6 and in the iodine derivative 8 Li and I can be replaced by hydrogen to form two isomers of the same composition 7 and 9, which differ only in the positions of the hydrogen and methyl groups with respect to Ge or N. The X-ray structure analyses on 4, 9, and 10 reveal that the germanium atom is fourfold coordinated by two nitrogen atoms and two other ligands. The intramolecular nitrogen base of the silazyl moiety in 1 and 2 is, thus, expelled from the coordination sphere of germanium by insertion of the double bonds into polar bonds, and the tricyclic molecule is changed to a bicyclic one. Thus these base stabilized bonds in 1 and 2 behave as normal unsaturated systems