Search results for "Reaction conditions"

2019

The preparation of unprecedented 6,12-disubstituted methanodibenzo[b,f][1,5]dioxocins from pyrrolidine catalyzed self-condensation of 2′-hydroxyacetophenones is herein described. This method provides easy access to this highly bridged complex core, resulting in construction of two C–O and two C–C bonds, a methylene bridge and two quaternary centers in a single step. The intricate methanodibenzo[b,f][1,5]dioxocin compounds were obtained in up to moderate yields after optimization of the reaction conditions concerning solvent, reaction times and the use of additives. Several halide substituted methanodibenzo[b,f][1,5]dioxocins could be prepared from correspondent 2′-hydroxyacetophenones.

Diastereoselective Synthesis of Spiro[pyrazolone-4,3′-tetrahydrothiophenes] via a Sulfa-Michael/Aldol Domino Reaction

2016

Synthesis : journal of synthetic organic chemistry 48(23), 4091-4098(2016). doi:10.1055/s-0035-1562473

Visible-light-accelerated amination of quinoxalin-2-ones and benzo[1,4]oxazin-2-ones with dialkyl azodicarboxylates under metal and photocatalyst-fre…

2021

A direct sp3 C-H amination of cyclic amines (dihydroquinoxalinones and dihydrobenzoxazinones) with dialkyl azo dicarboxylates accelerated by visible-light irradiation under metal and photocatalyst-free conditions is described. This protocol features very mild reaction conditions for the synthesis of aminal quinoxaline and benzoxazine derivatives with good to high yields (up to 99%). These aminal derivatives respresent versatile building blocks for the divergent synthesis of quinoxalin-2-one derivatives.

ChemInform Abstract: Reactions of 3-Vinylindole Derivatives with Dienophiles.

2010

Reactions of 3-(1-cyclohexenyl)-1,2-dimethylindole (1a) and the 1,2-dihydrocarbazole 1b with some carbo- and heterodienophiles are described. Thus, compound 1a reacts to give ene, Michael-type, and Diels-Alder adducts, depending on the dienophile and reaction conditions. The 3-vinylindole 1b reacts with 4-phenyl-1,2,4-triazoline-3,5-dione or N-phenylmaleimide in a dehydrogenative reaction to yield the fully aromatized carbazole 8.

Synthesis of Optically Pure Arylamine Derivatives by Using the Bucherer Reaction

2017

The Bucherer reaction is a common pathway for the conversion of 1- and 2-naphthols into the corresponding 1- or 2-naphthylamines, respectively. Mostly, only singular examples for its preparative use are reported since this particular transformation seems to be very sensitive to the reaction conditions. By choosing different phenolic substrates and chiral amines, we were able to prepare a broad scope of optically pure arylamines using this type of reaction. In contrast to alternative methods forming C−N aryl bonds such as Buchwald-Hartwig or Chan-Lam cross-coupling reactions, no palladium or copper catalysts are required. The use of water as solvent and the easily available starting material…

Palladium-Catalyzed N-Arylation Reactions with Aziridine and Azetidine

2007

Studies on the viability of palladium-catalyzed cross-coupling reactions of aryl- or hetaryl bromides with the parent aziridine or azetidine showed that a wide range of N-arylaziridines and N-arylazetidines are accessible by this method. Ring cleavage of the N-arylaziridines or -azetidines thus produced does not occur under the applied reaction conditions. The synthetic utility of the method is illustrated by examples of double N-arylations with either aziridine or azetidine.

Synthese und eigenschaften von einem nitrosubstituierten p-polyphenylen und von nitrosubstituierten p-oligophenylenen. 15. Mitteilung1

1964

Bei aromatischen Nitrojodverbindungen nimmt die ULLMANN-Reaktion unter verhaltnismasig milden Bedingungen einen praktisch quantitativen Verlauf, wenn sich das Jod in der o-Stellung zu einer Nitrogruppe befindet. Mit einer entsprechenden bifunktionellen Verbindung, dem 4,4′-Dijod-3,3′-dinitrobiphenyl, konnte unter den gleichen Bedingungen ein nitrosubstituiertes p-Polyphenylen erhalten werden, ein hellgelbes, unlosliches und unschmelzbares Pulver, das sich bei hoherer Temperatur (> 250°C) zersetzt. Auf Grund des Jodgehaltes (Endgruppen) wurde ein mittlerer Kondensationsgrad von 52 berechnet; das entspricht einer p-Phenylenkette aus 104 Benzolringen. Das Polymere ist kristallin und besitzt ei…

On the mechanism of the addition of organolithium reagents to cinnamic acids

2001

Abstract The regioselectivity of the addition of tert-butyllithium to cinnamic acid is subject to reaction conditions and to substituent electronic effects. Significant effects are observed in the presence of several additives including a radical trap such as α-methylstyrene. Competition experiments by addition of the organolithium reagent to mixtures of substituted cinnamic acids show that the relative rates of both conversion of the starting acids and formation of the 1,3-adducts are subject to electronic effects, whereas rates for 1,4-addition are independent of the substituents. These features are in agreement with a polar addition mechanism, but a fast SET equilibrium followed by slow …

The effect of trivalent framework heteroatoms in Cu-CHA on the Selective Catalytic Reduction of NO

2021

Abstract The effect of the trivalent framework atoms (Si4+/M3+ = 13-105) in Cu exchanged CHA-type zeolites was investigated for the selective catalytic reduction of NO with NH3. While the increased hydrophobicity of B-CHA compared to Al-CHA could make it a good candidate for low temperature SCR, the material was too unstable under reaction conditions and the exchanged Cu2+ did not remain isolated. Consequently a lower activity and selectivity than for Al-CHA were observed. Ga-CHA on the other hand showed a similar Cu2+ speciation as Al-CHA at similar Si4+/M3+ ratios. The difference in catalytic activity was remarkably small. While Ga-CHA was less stable upon hydrothermal aging, this was mar…

PHOSPHORORGANISCHE VERBINDUNGEN 115 WEGE ZUM ANALYTISCHEN NACHWEIS VON VERBINDUNGEN MIT DER P(O)F- UND P(O)SR-GRUPPE

1984

Abstract Acridine-9-hydroxamicacid 5 is suitable for the analytical detection of the model phosphorylfluorides 7 by fluorescence. The model compounds are rearranged according to Lossen and degradated to the fluorescent 9-aminoacridine 6 using defined reaction conditions. Thiophospho-S-esters (with diethyl-thiophosphinicacid-S-butylester 8 as a model compound) are cleaved to the corresponding phosphoryl-fluorides (a) and mercaptanes (b) by fluorolysis. (a) is identified qualitatively with acridine-9-hydroxamicacid 5, (b) by the Ellman-reaction. Zum Fluoreszenznachweis der Modellphosphorylfluoride 7 ist Acridin-9-hydroxamsaure 5 geeignet. Die Modellverbindungen 7 werden unter Einhaltung defin…