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Cyclic Secondary Amines (cyclic + secondary_amine)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

The use of MPA amide for the assignment of absolute configuration of a sterically hindered cyclic secondary amine by ,mix and shake' NMR method

MAGNETIC RESONANCE IN CHEMISTRY, Issue 1 2008
Jinhai Gao
Abstract We present here a new method using methoxyphenylacetic acid (MPA) as the chiral derivatizing agent (CDA) for the assignment of absolute configuration of cyclic secondary amines. The MPA amides were prepared using the purification-free ,mix and shake' method. A detailed conformational analysis for the two diastereomeric amides was conducted by 2D NMR experiments and molecular mechanics calculations. We have established that, in the most stable conformation of each syn rotamer of MPA amides, the H-, in the MPA moiety is oriented toward the bulky substituent group at the asymmetric carbon in the chiral amine, presumably to avoid steric and/or electrostatic interactions. The observed NMR data were correlated with the conformational model to allow unambiguous assignment of absolute configuration of secondary amines. The results demonstrate that the MPA can be used as a useful CDA in the case of sterically crowded cyclic secondary amines from which the MTPA amides are usually difficult to make. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Direct Amide Synthesis from Alcohols and Amines by Phosphine-Free Ruthenium Catalyst Systems

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009
Subhash Chandra Ghosh
Abstract Amides are synthesized directly from alcohols and amines in high yields using an in situ generated catalyst from easily available ruthenium complexes such as the (p -cymene)ruthenium dichloride dimer, [Ru(p -cymeme)Cl2]2, or the (benzene)ruthenium dichloride dimer, [Ru(benzene)Cl2]2, an N-heterocyclic carbene (NHC) ligand, and a nitrogen containing L-type ligand such as acetonitrile. The phosphine-free catalyst systems showed improved or comparable activity compared to previous phosphine-based catalytic systems. The in situ generated catalyst from [Ru(benzene)Cl2]2, an NHC ligand, and acetonitrile showed excellent activity toward reactions with cyclic secondary amines such as piperidine and morpholine. [source]

Synthesis, characterization and studies of new 3-benzyl-4H -1,2,4-triazole-5-thiol and thiazolo[3,2- b][1,2,4]triazole-5(6H)-one heterocycles

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2008
Abdelwareth A. O. Sarhan
3-Benzyl-4-phenyl-1,2,4-triazole-5-thiol (1) was synthesized and used as starting material for preparation of 1,2,4-triazole bearing substituted thiosemicarbazides moiety (4a-d) in high yields. The thiosemicarbazides 4a-d were cyclized in basic medium to give two triazole rings linked by thiomethylene group (5a-d), while cyclization of thiosemicarbazides 4a-d with chloroacetyl chloride in the presence of CHCl3 and K2CO3 afforded the thiazolidinone derivatives 6a-d. The reaction of thiosemicarbazides 4a-c with phenacyl bromide in the presence of EtOH and fused CH3COONa gave the corresponding thiazoline ring systems 7a-c. Condensation of the 3-benzyl-1,2,4-triazole-5(1H)-thiol (1) with chloroacetic acid and aromatic aldehydes (8a- g) in boiling acetic acid/acetic anhydride mixture in the presence of fused sodium acetate gave one single isomer only, which might be 9a-g or 10a-g. Upon application of Micheal addition reaction on compounds 9a-e with cyclic secondary amines such as piperidine or morpholine the 2-benzyl-6-(,-amino-aryl/methyl)-1,3-thiazolo[3,2- b][1,2,4]-triazol-5-ols (11a-j) were obtained in good yields The structure of all new compounds were determined using both spectral and elemental analyses. [source]

The use of MPA amide for the assignment of absolute configuration of a sterically hindered cyclic secondary amine by ,mix and shake' NMR method

MAGNETIC RESONANCE IN CHEMISTRY, Issue 1 2008
Jinhai Gao
Abstract We present here a new method using methoxyphenylacetic acid (MPA) as the chiral derivatizing agent (CDA) for the assignment of absolute configuration of cyclic secondary amines. The MPA amides were prepared using the purification-free ,mix and shake' method. A detailed conformational analysis for the two diastereomeric amides was conducted by 2D NMR experiments and molecular mechanics calculations. We have established that, in the most stable conformation of each syn rotamer of MPA amides, the H-, in the MPA moiety is oriented toward the bulky substituent group at the asymmetric carbon in the chiral amine, presumably to avoid steric and/or electrostatic interactions. The observed NMR data were correlated with the conformational model to allow unambiguous assignment of absolute configuration of secondary amines. The results demonstrate that the MPA can be used as a useful CDA in the case of sterically crowded cyclic secondary amines from which the MTPA amides are usually difficult to make. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Photochemical Key Steps in the Synthesis of Surfactants from Furfural-Derived Intermediates

CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 12 2009
Abdoulaye Gassama Dr.
Abstract Furfural is oxidized to 2[5H]-furanone by using hydrogen peroxide or to 5-hydroxy-2[5H]-furanone by using photo-oxygenation. An amine function is introduced by photochemically induced radical addition of tertiairy amines, some of which carry an n -alkyl side chain as hydrophobic moiety. These amines are produced from fatty aldehydes and cyclic secondary amines. The resulting adducts are transformed into amphoteric surfactants possessing an ammonium and a carboxylate function. Amphoteric (pKN and isoelectric point) and surfactant properties such as the critical micelle concentration and the adsorption efficiency are determined. [source]