Search results for "mannich"
showing 10 items of 33 documents
Organocatalyticanti-Selective Mannich Reactions with Fluorinated Aldimines: Synthesis ofanti-γ-Fluoroalkyl-γ-amino Alcohols
2009
The asymmetric Mannich reaction between fluoroalkyl aldimines and aldehydes catalyzed by α,α-diphenylprolinol trimethylsilyl ether is reported. The corresponding Mannich adducts were reduced in situ to afford anti-β-alkyl-γ-fluoroalkyl-γ-amino alcohols in moderate yields and with very high diastereo- and enantioselectivities. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Enantioselective Organocatalysis of Strecker and Mannich Reactions Based on Carbohydrates.
2007
Efficient organocatalysts for enantioselective Strecker and Mannich reactions were constructed from glucosamine as a readily accessible chiral scaffold. A variety of aromatic aldimines were subjected to hydrocyanation with good to excellent yield (72–98 %) and, in part, high enantioselectivity (69–95 % ee). Influence of the catalyst architecture on the enantioselectivity obviously arises from restrictions imposed on the conformational flexibility of the monosaccharidic backbone. In the asymmetric Mannich reaction moderate yields (up to 76 %) and enantioselectivities (up to 58 % ee) have been achieved with the described catalyst.
Stereoselective Total Synthesis of the Diastereomeric Tricyclic Alkaloids Tetraponerine-7 and Tetraponerine-8 Using O-Pivaloylated d-Arabinopyranosy…
2015
Based on a diastereoselective domino Mannich–Michael reaction cascade of 2- N -[( S )-3-{(benzyloxycarbonyl)[4-( tert -butyldiphenylsiloxy)butyl]amino}octylidene]-2,3,4-tri- O -pivaloyl-α- d -arabinopyranosylamine with the Danishefsky diene, the major component of the neurotoxic venom of the New Guinean ant Tetraponera punctulata , tetraponerine-8, and its diastereomer tetraponerine-7 were synthesized in pure form. While the Mannich reaction of the arabinosyl imine of the required ( S )-configured β-aminoaldehyde gave the 2-substituted piperidinone precursor of tetraponerine-8 with excellent diastereoselectivity, the analogous Mannich reaction of the ( R )-configured β-aminoaldehyde afforde…
A three-component Mannich-type condensation leading to phosphinic dipeptides—extended transition state analogue inhibitors of aminopeptidases
2011
Abstract N-Protected α-aminoalkylphosphinic acids bearing a P–H function were found to be novel practical building blocks in three-component condensations with formaldehyde and secondary amines (amino acids). Such Mannich-type N -phosphonomethylation is a common approach for phosphorus acid derived substrates and leads to multifunctional (phosphonic/amino/carboxylic) compounds of diverse relevance. The utility of this reaction was examined for construction, in a single synthetic step, of advanced phosphinic pseudodipeptides designed to act as extended transition state analogue inhibitors of selected aminopeptidases. Phosphinomethylation of primary amino acids was less efficient and yielded …
ChemInform Abstract: Organocatalytic anti-Selective Mannich Reactions with Fluorinated Aldimines: Synthesis of anti-γ-Fluoroalkyl-γ-amino Alcohols.
2010
The asymmetric Mannich reaction between fluoroalkyl aldimines and aldehydes catalyzed by α,α-diphenylprolinol trimethylsilyl ether is reported. The corresponding Mannich adducts were reduced in situ to afford anti-β-alkyl-γ-fluoroalkyl-γ-amino alcohols in moderate yields and with very high diastereo- and enantioselectivities. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Antimykotische Wirkstoffe, 16. Mitt. Halogenierte Cyanaminomethylenpiperidine und -piperazine
1984
Die in Gegenwart der sekundaren Amine 5a-e mit Hilfe von s-Triazin (2) als Dreikomponentenreaktion durchgefuhrte Aminomethinylierung von Cyanamid (1) liefert die korrespondierenden als Dehydro-N-Mannich-Basen aufzufassenden Cyanaminomethylenheterocyclen 6a-e. Insbesondere 6a und 6e besitzen antimykotische Wirksamkeit. Antimycotic Agents, XVI: Halogenated (Cyanaminomethylene)piperidines and -piperazines The aminomethinylation of cyanamide (1) by means of s-triazine (2), carried out as three-component reaction in the presence of the secondary amines 5a–e, yields the cyanaminomethylene heterocycles 6a–e, which are to be classed as dehydro-N-Mannich bases. Compounds 6a and 6e in particular show…
ChemInform Abstract: A Decade of Advance in the Asymmetric Vinylogous Mannich Reaction
2016
When the principle of vinylogy is applied to imines as electrophiles, the so-called vinylogous Mannich reaction (VMR), γ-aminocarbonyl (such as butenolides) and β-aminocarbonyl compounds are generated in a very efficient manner. The asymmetric version of this vinylogous Mannich reaction gives access to highly functionalized chiral synthons, which are suitable for further transformations. The versatility of this methodology is exemplified with the synthesis of several alkaloids and natural products. 1 Introduction 2 Asymmetric Vinylogous Mannich Reactions (VMR) with 2-Silyloxyfurans and 2-Silyloxypyrroles 3 Asymmetric VMR with Acyclic Silyl Dienolates and Silyl Dienol Ketene Acetals 4 Asymm…
Ringoffene Serotonin-Analoga, 2. Mitt.1) Synthese von 3-(2-Aminophenyl)-propanamin- und 1-(N-Piperidino)-3-(2-aminophenyl)-3-oxo-propan-Derivaten
1983
Die Darstellung der Titelverbindungen gelingt via Mannich-Reaktion beim Einsatz geeignet substituierter Acetophenone. Die Gewinnung von 2 und seiner Derivate erfordert zusatzlich die nachfolgende durchgreifende Hydrierung der Carbonylgruppe der entsprechenden Mannichbasen. Ring-Opened Analogues of Serotonine, II: Synthesis of 3-(2-Aminophenyl)propanamine and 1-(Piperidin-1-yl)-3-(2-aminophenyl)propan-3-one and Their Derivatives The synthesis of the title compounds was achieved by Mannich reaction of suitably substituted acetophenones. The preparation of 3-(2-aminophenyl)propanamine and its derivatives requires complete hydrogenation of the carbonyl group of the Mannich bases.
Crystal structure and Hirshfeld surface analysis of 3-octyl-4-oxo-2,6-bis(3,4,5-trimethoxyphenyl)piperidinium chloride
2018
The title compound was synthesized by a one-pot Mannich condensation reaction. In the crystal, centrosymmetric dimers are linked into layers parallel to (011) by N—H⋯Cl and C—H⋯Cl hydrogen bonds. A Hirshfeld surface analysis indicates that O—H (20.5%) interactions make the largest contribution to the crystal packing.
Organocatalysts Fold to Generate an Active Site Pocket for the Mannich Reaction
2017
Catalysts containing urea, thiourea and tertiary amine groups fold into a three-dimensional organized structure in solution both in the absence as well as in the presence of substrates or substrate analogues, as indicated by solution NMR and computational studies. These foldamer catalysts promote Mannich reactions with both aliphatic and aromatic imines and malonate esters. Hammett plot and secondary kinetic isotope effects provide evidence for the C-C bond forming event as the turnoverlimiting step of the Mannich reaction. Computational studies suggest two viable pathways for the C-C bond formation step, differing in the activation modes of the malonate and imine substrates. The results sh…