1,721,021 research outputs found
Structural Characterization and Regiochemical Differentiation of α-Cyanoethylindole Isomers in the Gas Phase
No full textass spectrometry and tandem mass spectrometry techniques have been used to study the gas phase ion chemistry of isomeric α-cyanoethylindoles obtained by photochemical reactions. Both the fragmentation reactions occurring in the ion source, as well as metastable decompositions produced by the molecular and selected fragment ions, have allowed us to structurally characterize and differentiate each isomer from the others. The experiments, carried out also on deuterium labeled analogs, have shown the role exerted by the α-cyanoethyl substituent and by its position at the indolic ring on gas phase reactions that resulted to be distinctive and selective for each isomer. Ab initio theoretical calculations have been used to evaluate the stability and chemico-physical properties of different ion structures. © 2004 American Society for Mass Spectrometry
New Mild and Efficient Synthesis of Peptidosulfonamides
No full textThis article describes a new route to peptidosulfonamide. Our study shows how sulfinamides were first obtained via nucleophilic cleavage of 3,6-dihydrothiazine-1-oxide system and how the products can be subjected to oxidation with m-chloroperbenzoic acid to give sulfonamides in good yield. Copyright © Taylor & Francis Group, LLC
3-oxo-3-thia-2-azabicyclo[2.2.1]hept-5-en-2-carboxylates: the first isolation and characterization
No full textMethyl and benzyl 3-oxo-3-thia-2-azabicyclo[2.2.1]hept-5-en-2-carboxylate were isolated at r.t. and characterized for the first time. Both endo and exo- isomers were observed. In suitable experimental conditions (stoichiometric amount of sodium acetate, –40°C or sodium borohydride/methyl iodide) ring opening of these compounds gave the corresponding thiosulfonates or methyl sulfides, respectivel
1,2- and 1,3-oxazolopyridines: versatile building blocks for the heterocyclic synthesis
No full text1,3- And 1,2-oxazolopyridines are well known and characterized class of heterocyclic compounds having a wide range of properties and applications. Different reactions, mainly consisting in derivatization/cyclization of suitable acyclic compounds, can be used for their preparation. Both thermal and photochemical modifications of their annular system are possible, opening the easy access to a wide family of monocyclic and condensed ring systems. © 2006 Societa Chimica Italiana
New Derivatives of 3-Methylisoxazolo[5,4-b]pyridines
No full textThe synthesis and properties of 4,6‐dichloro‐ (IV), 4‐chloro‐ (XII) and 6‐chloro‐3‐methyl‐isoxazolo[5,4‐b]pyridine (XI) are described. Depending on the reaction conditions compound IV with hydrazine or methoxide gave mono‐ or bi‐substituted products. The halogen atom at the 4‐position was shown to be the more mobile. Copyright © 1977 Journal of Heterocyclic Chemistr
Photochemistry of 4,6-Diazido-3-methylisoxazolo[4,5-c]pyridines: a convenient entry to 3-Methylisoxazolo[1,3]diazepine system
No full textUV irradiation of 4,6-diazido-3-methylisoxazolo[4,5-c] pyridine in methanol gives the 3-methylisoxazolo-1,3-diazepine derivatives 3,4 by nitrogen loss and solvent addition
Diastereoselective synthesis of beta-aminocyclopentene sulfonic acid via hetero Diels-Alder reaction
No full textA new cyclopentene GABA analogue was synthesized as a conformationally rigid analogue of the epilepsy drug vigabatrin. N-Sulfinyl dienophile Diels-Alder methodology, followed by alkaline hydrolysis of the corresponding dihydrothiazine oxide, oxidation and deprotection of the amino group gave cis-4-aminocyclopent-2-ene-1-sulfonic acid. The corresponding N,N-dimethylsulfinamide was also obtained. © 2006 Elsevier Ltd. All rights reserved
Hydrolysis of Methylthiazolopyridines. X-ray Crystal Structure of 3-Acetamido-2(1H)-pyridinethione
No full textHydrolysis of 2-methylthiazolo[5,4-b]pyridine resulted in ring opening of the thiazole and formation of 3-acetamido-2(1H)-pyridinethione whose X-ray crystal structure has been determined
Tetrahydropyridinium bromide: useful synthon to functionalized pyridines
No full text1-benzyl-5-(ethoxycarbonyl)-2,3,4,5-tetrahydropyridinium bromide undergoes ring contraction with a
series of nucleophiles, getting 2,2-disubstitued pyrrolidines. Moreover, from some of the new 2,2-disubstitued
pyrrolidines were synthesized spiro-pyrrolidine
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