Search results for "DISCOVERY"
showing 10 items of 4119 documents
Tetramethylguanidine (TMG)-catalyzed addition of dialkyl phosphites to α,β-unsaturated carbonyl compounds, alkenenitriles, aldehydes, ketones and imi…
1998
Abstract Tetramethylguanidine-catalyzed addition of dialkyl phosphites to α,β-unsaturated carbonyl compounds, alkenenitriles, aldehydes and ketones constitutes a practical route to a variety of phosphonate synthons. The very mild conditions employed, together with the short reaction times, make the procedure highly versatile and tolerant to a range of functionalities. The proposed methodology is also convenient for the preparation of α-aminophosphonates.
Efficient preparation of 4-methoxy-5,6-dihydro-2H-pyran
2008
Abstract We report the efficient synthesis of 4-methoxy-5,6-dihydro-2 H -pyran (MDHP) via the TiCl 4 driven elimination of MeOH from 4,4-dimethoxytetrahydropyran. The previous difficulty of preparing MDHP restricted the wider use of 4-methoxytetrahydropyran-4-yl (MTHP) acyclic acetals, which have desirable protecting group properties when compared to more commonly used MOM- and THP-acetals. The behaviour of the elimination on related acetals is also examined.
Advances in singlet oxygen chemistry
2005
The authors discuss the advances made in both mechanistic and synthetic aspects of singlet oxygen chem. Formation and reactions of singlet oxygen in heterogeneous media (such as zeolites, micelles, vesicles, etc.) are discussed. Cycloaddns. of mol. oxygen to olefins, heteroatom oxidns. via reaction of singlet oxygen with the electron pair at heteroatoms, and photooxygenations of heterocyclic systems by singlet oxygen are also reviewed.
Antivirale Wirkstoffe, 17. Mitt. Oligocyclisch N-substituierte Lithocholsäureamide
1981
Von den durch Umsetzung der 3-Formyllithocholsaure mit den entsprechenden Aminen erhaltenen oligocyclisch N-substituierten Lithocholsaureamiden 1 uben insbesondere N-(2-Naphthyl)-3-formyllithocholsaureamid (1b) und N-(endo-2-Methylbicyclo[2.2.1]heptyl)lithocholsaureamid (1c) markante virustatische Wirkungen aus. Antiviral Drugs, XVII: Oligocyclically N-Substituted Lithocholic Amides Oligocyclically N-substituted lithocholic amides 1 are obtained by the reaction of 3-formyllithocholic acid with amines. N-(2-Naphthyl)-3-formyllithocholic amide (1b) and N-(endo-2-methylbicyclo-[2.2.1]heptyl)lithocholic amide (1c) exhibit marked virustatic activity.
Struktur-Wirkungs-Beziehungen bei Analeptica vom Typ des Nicethamids, 3. Mitt. Synthese von Analogen des 6-Methyl-nicethamids
1975
Als potentiell analeptisch wirksame Substanzen mit partiell fixierter funktioneller Gruppe werden strukturanaloge Amide, Imide und Lactame des 2-Methyl-nicethamids synthetisiert. Synthesis of 2-Methyl-Nicethamide Analogues. As potentially analeptically active substances with partially fixed functional groups, structural analogues of 2-methyl-nicethamide, in the form of amides, imides and lactams, are synthesized.
Verbindungen mit potentiell positiv inotroper Wirkung, 1. Mitt. N-Substituierte 3-Amino-2-cyclopentenone aus partiell hydrierten 2-Phenanthrylaminen
1984
Die Darstellung partiell hydrierter 2-Phenanthrylamine und ihre Umsetzung mit 1,3-Cyclopentandion zu N-subst. 3-Amino-2-cyclopentenonen wird beschrieben. Compounds with Potentially Positive Inotropic Activity, I: N-Substituted 3-Amino-2-cyclopentenones from Partially Hydrogenated 2-Phenanthrylamines The synthesis of partially hydrogenated 2-phenanthrylamines and their reactions with 1,3-cyclopentanedione to N-substituted 3-amino-2-cyclopentenones is described.
Massenspektrometrische Untersuchungen an Edukten für die Synthese H2-aktiver Substanzen
1982
Unter den Bedingungen der Elektronenstosionisation wurden 4-[(2-Aminoethoxy)-methyl]-5-methyl-imidazo (1), die Imidazolderivate mit N-substituierter Ethylendiamin-Struktur 2–5 sowie die Imidazolcarboxamide 6–8 massenspektrometrisch untersucht. Der Mechanismus der konkurrierenden Bindungsspaltungen und der Umlagerungsprozesse wird formuliert. Die Wechselwirkung der funktionellen Gruppen sowie deren Einflus auf das Fragmentationsverhalten der Substanzen wird beschrieben und ein Schema der Hauptfragmentierungswege vorgeschlagen. Mess Spectrometry of Reactants for the Synthesis of H2-Active Compounds 4-[(2-Aminoethoxy)methyl]-5-methylimidazole (l), the imidazoles 2-5 with N-substituted ethylene…
Histaminähnliche Verbindungen mit cyclisierter Seitenkette 1. Mitt. über Struktur-Wirkungs-Beziehungen bei Histaminanaloga
1973
Als potentiell histaminartig wirksame Substanzen wurden 4-substituierte Piperidyl- und Aminocyclohexyl-imidazole dargestellt. Von diesen erwiesen sich 4-(3-Piperidyl)-imidazol (4b) und 4-(2-Aminocyclohexyl)-imidazol (8a) als histaminomimetisch wirksam. Uber Struktur-Wirkungs-Beziehungen der Histaminanaloga mit cyclisierter Seitenkette des Histaminmolekuls wird be richtet. Histamine-like Compounds with Cyclized Side Chain As substances with possible histamine-like activity 4-substituted piperidyl- and aminocyclohexyl-imidazoles were prepared. Two of them, 4-(3-piperidyl)-imidazole (4b) and 4-(2-aminocyclohexyl)-imidazole (8a), have histamine-like activity. Structure-action relationships of h…
A DFT study for the formation of imidazo[1,2-c]pyrimidines through an intramolecular Michael addition
2006
The formation of imidazo[1,2-c]pyrimidines through a ring closure of 2-(2-sulfonylimino-1,2-dihydro-1-pyrimidinyl) acetamides has been studied using DFT methods. Analysis of the energy results for the cyclization step shows the demand of almost an acid catalyst, which increases the electrophilicity of the dihydropyrimidine moiety, in order to make feasible the intramolecular Michael addition. The substitution on both dihydropyrimidine and amide moieties has also an influence on the cyclization step.
Bonandiol: A new, irregular, monocyclic diterpene from (L.) Halacsy (umbelliferae)
1984
A new, irregular, monocyclic diterpene, bonandiol (1), has been isolated from Bonannia graeca. The structure of bonandiol has been deduced from spectral data and chemical evidence.