Search results for "medicinal"

Redox-induced coordination isomerization of a phosphoniobenzophospholide.

2003

1-Triphenylphosphoniobenzo[c]phospholide 1 reacts with [M(CO)(5)Br] (M = Mn, Re) and [Mn(CO)(3)(naphthalene)][BF(4)] to give complexes cis-[M(CO)(4)(1)Br] (5 a,b) and [Mn(CO)(3)(1)][BF(4)] (6 a[BF(4)]), respectively, featuring eta(1)(P)- and eta(5)(pi)-coordination of the phosphole ring. The corresponding reactions with [M(2)(CO)(10)] proceed with conservation of the metal-metal bond and yield, depending on the reaction temperature, dinuclear complexes [M(2)(CO)(8)(1)] (M=Mn, 7 a) or [M(2)(CO)(6)(1)(2)] (M=Mn, Re, 8 a,b) with mu(2)-bridging eta(1)(P):eta(2)(Pdbond;C) coordination of the phosphole moiety. All complexes formed were characterized by spectroscopic data; 5 b, 6 a[BF(4)], and 8 a…

Naphthothiete und ihre Anwendung in der Heterocyclen-Synthese

1995

Naphtothietes and Their Application to the Synthesis of Heterocycles The three isomeric naphthothietes 5, 11, and 16 were prepared according to the reaction sequences shown in Schemes 1–3. The final step was in each case a flash vacuum pyrolysis (FVP) of the corresponding mercaptonaphthalenemethanol 4, 9, and 15, respectively. The thiete rings in 5 and 11 can be opened by gentle heating; the ring opening of the isomer 16 possesses a much higher activation barrier. A MNDO calculation of the ΔHf values of 5, 11, and 16 and the open isomers 5′, 11′, and 16′ provides an explanation for the different behavior. Photochemical ring opening represents a useful alternative. The reaction Schemes 4, 6,…

ChemInform Abstract: Cycloaddition Reactions of Benzothiete and Hetero Dienophiles for the Synthesis of Heterocyclic Systems.

1987

Abstract Benzothiete ( 1 ) undergoes cycloaddition reactions with hetero dienophiles with NN-, NO- or CO- double bonds, leading to six-membered heterocyclic ring systems of 2H-3,4-dihydro-1,2,3-benzothiadiazine ( 3 ), 4H-3,1,2-benzoxathiazine ( 4 ) and 4H-3,1-benzoxathiin.

Cycloaddition Reactions of 2H-Benzo[b]thiete and Thiocarbonyl Compounds

1997

2H-Benzo[b]thiete (1) reacts in the o-quinoid form 1′ with the cyclic trithiocarbonates 4 and 6a, b and with the thioketones 8, 10 and 12 in [8π + 2π] cycloaddition reactions to the spiro compounds 5, 7a, b, 9, 11a, b. Irrespective of the presence of CC double bonds, chemoselective and regioselective addition processes at the CS double bonds take place that lead to 4H-1,3-benzodithianes.

[3+2] Cycloaddition Reaction of C -Phenyl-N -methyl Nitrone to Acyclic-Olefin-Bearing Electron-Donating Substituent: A Molecular Electron Density The…

2018

ChemInform Abstract: Lithium Enediolates and Dienediolates of Carboxylic Acids in Synthesis: Alkylation with Secondary Halides.

2010

Abstract High yields in the alkylation of dianions of α,β-unsaturated carboxylic acids with secondary halides can be obtained despite elimination reactions occurring. α-Regioselectivity for the alkylation of but-2-enoic acids ( 1–4 ) is seldom obtained. Although double bond stereoselectivity is higher than 99% for γ-alkylated products, stereoselectivity is rather poor for most of the α-alkylated products.

Reaktive Metabolite cancerogener polycyclischer Kohlenwasserstoffe: Synthese und Abfangreaktion von 9-Hydroxybenzo[a]pyren-4,5-oxid

1985

Le compose du titre est prepare a partir de l'acetate-9 de benzo [a] pyrene et piege par l'ethanethiol. Mecanismes

2-Chloro/phenyl-7-arylimino-6,6-dimethylcyclopenta[b]pyridylnickel chlorides: Synthesis, characterization and ethylene oligomerization

2017

Abstract 2-Chloro/phenyl-7-arylimino-6,6-dimethylcyclopenta[b]pyridylnickel chlorides (Ni1–Ni8) were synthesized from the respective ligands L1–L8 and characterized. Upon activation with either methylaluminoxane (MAO) or ethylaluminium sesquichloride (EASC), they show high catalytic activity of up to 10.84 × 106 g(oligomer) mol− 1(Ni) h− 1 in ethylene oligomerization. The products range from butenes to dodecenes for Ni1–Ni4, but are limited to butenes and hexenes in the case of Ni5–Ni8. DFT calculations indicate that the Ni C bond length in the model alkyl complexes depends both on the nature of the substituents at the heterocycles and the kind of the alkyl group, shedding some light on the…

A molecular electron density theory study of the participation of tetrazines in aza-Diels–Alder reactions

2020

The reactions of eight tetrazines of increased electrophilic character with nucleophilic tetramethyl ethylene (TME) and with electrophilic tetracyanoethylene (TCE) have been studied using Molecular Electron Density Theory. These reactions are domino processes comprising an aza-Diels–Alder (ADA) reaction followed by an extrusion of molecular nitrogen, yielding a dihydropyridazine. Analysis of the conceptual DFT (CDFT) indices showed an increase of the electrophilicity and a decrease of the nucleophilicity of tetrazines with an increase of the electron-withdrawing character of the substituent. A very good correlation between the global electron density transfer at the transition structu…

Synthesis of enol esters catalysed by 'early–late' Ti–Ru complexes

2003

Abstract The titane–ruthenium heterobimetallic compounds ( p -cymene)[(η 5 -C 5 H 5 )(μ-η 5 :η 1 -C 5 H 4 (CH 2 ) m PR 2 )TiCl 2 ]RuCl 2 4 – 6 have been revealed to be quite good catalysts for the addition of formic acid to 1-hexyne and phenylacetylene. These preliminary results led us to synthesize new tetrametallic complexes 10 – 12 via the reaction of the titanocene phosphanes 1 – 3 with the polymer [Ru(CO) 2 (μ-O 2 CH)] n . Their catalytic ability for the enol esters formation has been studied.