نتایج جستجو برای: knorr condensation
تعداد نتایج: 32579 فیلتر نتایج به سال:
TiCl2/nano-γ-Al2O3 as a new heterogeneous Lewis acid catalyst was synthesized and characterized by FE-SEM, XRD, FT-IR, EDS, XRF, BET and TGA. N-substituted pyrroles have been synthesized via Paal–Knorr reaction in the presence of TiCl2/nano-γ-Al2O3 at room temperature under solvent-free conditions.
THE TITLE COMPOUND [SYSTEMATIC NAME: (2R,3R,4S,5R,6R)-2-(acet-oxy-meth-yl)-6-propoxytetra-hydro-2H-pyran-3,4,5-triyl triacetate], C(17)H(26)O(10), was formed by a Koenigs-Knorr reaction of 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide and n-propanol. The central ring adopts a chair conformation. The crystal does not contain any significant inter-actions such as hydrogen bonds.
Julia Kabuss,1 Dmitry O. Krimer,2 Stefan Rotter,2 Kai Stannigel,3 Andreas Knorr,1 and Alexander Carmele1,3 1Nichtlineare Optik und Quantenelektronik, Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany 2Institute for Theoretical Physics, Vienna University of Technology, Wiedner-Hauptstraße 8-10/136, A-1040 Vienna, Austria 3Institute for Qu...
The reductive coupling of enones or enals with alkynes, followed by olefin oxidative cleavage and Paal-Knorr cyclization, provides a versatile entry to a variety of pyrrole frameworks. A number of limitations of alternate entries to the requisite 1,4-dicarbonyl intermediate are avoided. Classes of pyrroles that are accessible by this approach include 2,3-, 2,4-, 1,2,3-, 1,2,4-, 2,3,5-, and 1,2,...
introduction: the purpose of this study was to evaluate the sealing ability of 3 obturation techniques in oval-shaped canals by bacterial leakage assessment. methods: sixty mandibular incisors with oval canals were selected after providing buccolingual and mesiodistal radiographs. the teeth were sectioned at a 10 mm distance from the apex. after instrumentation, the teeth were divided into 3 gr...
Lead authors : Howard I. Browman, Sam Dupont, Jon Havenhand, Lisa Robbins Contributing authors : Michael Beman, Carlos Duarte, Maoz Fine, Jan Helge Fosså, Jason Hall-Spencer, Pamela HallockMuller, Thomas P. Hurst, Debora Iglesias-Rodriguez, Paul Knorr, Haruko Kurihara, John Lisle, Clara Manno, Sophie McCoy, Frank Melzner, Philip Munday, Hans-Otto Pörtner, Justin Ries, Dominique Robert, Jeffrey ...
J. Lademann*, F. Knorr*, H. Richter*, S. Jung*, M. C. Meinke*, E. Rühl, U. Alexiev, M. Calderon and A. Patzelt* *Center of Experimental and Applied Cutaneous Physiology Department of Dermatology, Venereology and Allergology Charit e – Universit€ atsmedizin Berlin Charit eplatz 1, Berlin 10117, Germany Physical Chemistry, Institute of Chemistry and Biochemistry Freie Universit€ at Berlin Takustr...
One pot syntheses of furan, thiophene, and pyrrole were accomplished by oxidative deacetylation using Mn(III)/Co(II) catalysts and the Paal-Knorr reaction from 1,5-dicarbonyl compounds, which are prepared from the conjugate addition of ethyl acetoacetate to α,β-unsaturated carbonyl compounds. The oxidative deacetylation and reductive cyclization of β-ketoesters derived from ethyl acetoacetate a...
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