4747-81-3Relevant articles and documents
Dipole-Induced Rectification Across AgTS/SAM//Ga2O3/EGaIn Junctions
Baghbanzadeh, Mostafa,Belding, Lee,Yuan, Li,Park, Junwoo,Al-Sayah, Mohammad H.,Bowers, Carleen M.,Whitesides, George M.
supporting information, p. 8969 - 8980 (2019/06/13)
This Article describes the relationship between molecular structure, and the rectification of tunneling current, in tunneling junctions based on self-assembled monolayers (SAMs). Molecular dipoles from simple organic functional groups (amide, urea, and thiourea) were introduced into junctions with the structure AgTS/S(CH2)nR(CH2)mCH3//Ga2O3/EGaIn. Here, R is an n-alkyl fragment (-CH2-)2?or?3, an amide group (either -CONH- or -NHCO-), a urea group (-NHCONH-), or a thiourea group (-NHCSNH-). The amide, urea, or thiourea groups introduce a localized electric dipole moment into the SAM and change the polarizability of that section of the SAM, but do not produce large, electronically delocalized groups or change other aspects of the tunneling barrier. This local change in electronic properties correlates with a statistically significant, but not large, rectification of current (r+) at ±1.0 V (up to r+ ≈ 20). The results of this work demonstrate that the simplest form of rectification of current at ±1.0 V, in EGaIn junctions, is an interfacial effect, and is caused by a change in the work function of the SAM-modified silver electrode due to the proximity of the dipole associated with the amide (or related) group, and not to a change in the width or mean height of the tunneling barrier.
Efficient synthesis of 2,9-disubstituted 8-hydroxyadenine derivatives
Hirota, Kosaku,Kazaoka, Kazunori,Niimoto, Itaru,Sajiki, Hironao
, p. 1354 - 1365 (2007/10/03)
An efficient and general method for the synthesis of 2,9-disubstituted 8-hydroxyadenines, which are expected to have various biological activities, was realized. 5-amino-4-cyano-2-hydroxyimidazoles(1) were prepared from aminomalononitrile and isocyanates as key intermediates. The condensation of 1a with amidines, imidates, guanidine, urea and thioureas afforded 8-hydroxyadenines (2-6) possessing various substituents at the 2-position. Furthermore, selective alkylation of 2-amino- and 2-hydroxyadenines (4 and 6) successively proceeded to give the corresponding 2-alkylamino- and 2-alkoxyadenines (5 and 7), respectively. 2-Alkythioadenines (15) were prepared by an analogous reaction of 1a with benzoyl isothiocyanate and subsequent S-alkylation. The imidazoles 1 are most useful intermediated for the synthesis of 8-hydroxyadenine derivatives.
Radical Azidonation of Aldehydes
Marinescu, Lavinia,Thinggaard, Jacob,Thomsen, Ib B.,Bols, Mikael
, p. 9453 - 9455 (2007/10/03)
Aliphatic and aromatic aldehydes can be converted to acyl azides by treatment with iodine azide at 0-25°C. If the reaction is performed at reflux Curtius rearrangement occurs and carbamoyl azides are obtained in 70-97% yield from the aldehyde. The reaction was shown to have a radical mechanism.
Development of chiral N-alkylcarbamates as new leads for potent and selective H3-receptor antagonists: Synthesis, capillary electrophoresis, and in vitro and oral in vivo activity
Sasse, Astrid,Kiec-Kononowicz, Katarzyna,Stark, Holger,Motyl, Malgorzata,Reidemeister, Sibylle,Ganellin, C. Robin,Ligneau, Xavier,Schwartz, Jean-Charles,Schunack, Walter
, p. 593 - 600 (2007/10/03)
Novel carbamates as derivatives of 3-(1H-imidazol-4-yl)propanol with an N-alkyl chain were prepared as histamine H3-receptor antagonists. Branching of the N-alkyl side chain with methyl groups led to chiral compounds which were synthesized stereospecifically by a Mitsunobu protocol adapted Gabriel synthesis. The optical purity of some of the chiral compounds was determined (ee > 95%) by capillary electrophoresis (CE). The investigated compounds showed pronounced to high antagonist activity (K(i) values of 4.1-316 nM) in a functional test for histamine H3 receptors on rat cerebral cortex synaptosomes. Similar H3-receptor antagonist activities were observed in a peripheral model on guinea pig ileum. No stereoselective discrimination for the H3 receptor for the chiral antagonists was found with the in vitro assays. All compounds were also screened for central H3-receptor antagonist activity in vivo in mice after po administration. Most compounds were potent agents of the H3-receptor-mediated enhancement of brain N(τ)- methylhistamine levels. The enantiomers of the N-2-heptylcarbamate showed a stereoselective differentiation in their pharmacological effect in vivo (ED50 of 0.39 mg/kg for the (S)-derivative vs 1.5 mg/kg for the (R)- derivative) most probably caused by differences in pharmacokinetic parameters. H1- and H2-receptor activities were determined for some of the novel carbamates, demonstrating that they have a highly selective action at the histamine H3 receptor.
Stereoselective synthesis of glycosyl carbamates as new surfactants and glycosyl donors
Prata, Caria,Mora, Nathalie,Lacombe, Jean-Michel,Maurizis, Jean Claude,Pucci, Bernard
, p. 8859 - 8862 (2007/10/03)
O-acyl-protected glycosyl N-alkyl and N-phenyl carbamates are obtained with 100% diastereoselectivity from anomerically unprotected mono or disacacharides. Long-chain alkyl carbamates are surfactants. N-phenyl carbamates are good glycosyl donors.
The Conversion of Carboxylic Acids into Isonitriles via Selenium-Phenyl Selenocarbamates
Barrett, Anthony G. M.,Kwon, Hyok,Wallace, Eli M.
, p. 1760 - 1761 (2007/10/02)
Carboxylic acids are converted into isonitriles via Schmidt rearrangement of the derived acyl azides, addition of phenylselenol to the resultant isocyanate, tributylstannane reduction and dehydration.
Oxidation of aldehydes to acyl azides by chromic anhydride-azidotrimethylsilane
Lee,Kwak
, p. 3165 - 3166 (2007/10/02)
Aldehydes are efficiently oxidized to acyl azides by azidotrimethylsilane and chromic anhydride at room temperature (aromatic), or at -10°C (aliphatic).
CHIMIE DES SUCRES SANS GROUPEMENTS PROTECTEURS-II REACTIONS SELECTIVES D'ADDITION DU D-GLUCOSE, DU D-GALACTOSE ET DE D-GLYCOSYLAMINES A DES HETEROCUMULENES
Plusquellec, Daniel,Roulleau, Fabienne,Lefeuvre, Martine,Brown, Eric
, p. 465 - 474 (2007/10/02)
Alkyl isocyanates reacted with 1.5 equivalent of α-methylglucoside, glucose or galactose in pyridine at room temperature, and selectively gave the corresponding 6-N-alkylcarbamates in good yields.The readily available glucosylamine and lactosylamine (1.5-2 eq.) reacted with alkyl isocyanates and isothiocyanates in polar aprotic solvents (pyridine, NMP or DMF), thus affording good yields of the corresponding N-glycosyl N'-alkyl ureas and thioureas.These new sugar derivatives are non-ionic detergents.
SYNTHESE ET THERMOLYSE DE DERIVES DISILYLES DES ACIDES HYDROXAMIQUES: SUR UNE NOUVELLE VOIE D'ACCES AUX ESTERS ISOCYANIQUES ET AUX AMINES
Rigaudy, J.,Lytwyn, E.,Wallach, P.,Cuong, Nguyen Kim
, p. 3367 - 3370 (2007/10/02)
Thermolysis of disilylated hydroxamic acids 7, readily prepared from hydroxamic acids 5 and hexamethyl disilazane, leads to the corresponding isocyanates 4; an application to the synthesis of amines is reported.
SYNTHESIS OF ALIPHATIC ISOCYANATES VIA A TWO-PHASE HOFMANN REACTION
Sy, Anita O.,Raksis, Joseph W.
, p. 2223 - 2226 (2007/10/02)
A convenient method of preparing aliphatic isocyanates via a two-phase Hofmann reaction using a phase transfer catalyst is described.
