Über O‐acylierte Hydroximsäure‐ester und ihre Spaltung zu unsubstituierten O‐Acylhydroxylaminen. X. Mitteilung über Hydroxylamin‐Derivate

Abstract

Im Gegensatz zu den Hydroxamsauren (I) sind von den ihnen isomeren unsubstituierten 0-Acylhydroxylaminen (11) bisher nur wenige Vertreter bekanntgewor-Als Ausgangsstoff fur eine neue Synthese solcher 0-Acylhydroxylamine dientmir Acethydroximsaure-athylester (IV)5), der sich leicht in 0-Acyl-Derivate (V) iiberfuhren lieP). Diese Verbindungen sind den 0-Acyl-Derivaten VII des Acetonoxims (VI) sehr ahnlich; das IR-Spektrum zeigt die C=O-Valenzschwingung an der gleichen Stelle wie bei diesen. Die C= N-Valenzschwingung ist dagegen etwas langerwellig verschoben, wahrend sie bei den niclit acylierten Grundverbindungen ubereinstimmt :

Prodrug design for the potent cardiovascular agent Nω-hydroxy-l-arginine (NOHA): Synthetic approaches and physicochemical characterization

“…Initial attempts to apply the above described synthetic strategy (see Scheme 1) failed since, in our hands, the required O-acylated hydroxylamines could not be prepared according to a literature procedure. 38 We were unable to deprotect several O-acylated ethyl imidates using HCl in different solvents, such as nitromethane, diethyl ether, or 1,4-dioxane. They were not commercially available, and thus, other approaches were pursued.…”

Nucleophilic Displacement Reactions at the Thiolester Bond. III.1 Kinetic Demonstration of Metastable Intermediates in the Hydroxylaminolysis and Methoxylaminolysis of Thiolesters and Thiolactones in Aqueous Solutions

“…•¿Va (17) &obsd _ &I + ^II®H + ^IIlOH2 (RÑhT2 _ feiv + aH (18) possesses the same mathematical form as 5a. The rate expression derived from 17 under the limiting conditions of Oh = 0 and <Zh = 03 are provided by 19a and 19b, respectively, which are expressions for general base and general acid catalyzed nucleophilic reactions.…”

Direct and Catalytic Amide Synthesis from Ketones via Transoximation and Beckmann Rearrangement under Mild Conditions

“…H 2 18 O used was 99% 18 O-labeled water made by Taiyo Nippon Sanso Corporation. Most of the amides were characterized by 1 H NMR for comparison to previous reports. ,,,,,,− …”

“…Ethyl O-Benzoyl Acetohydroxamate (2c). 25 White solid (2.41 mmol scale, 455 mg, 91%). 1 H NMR (400 MHz, CDCl 3 ) δ 8.06 (d, J = 8.2 Hz, 2H), 7.58 (t, J = 8.2 Hz, 1H), 7.46 (t, J = 7.3 Hz, 1H), 4.29 (q, J = 7.1 Hz, 2H), 2.16 (s, 3H), 1.36 (t, J = 7.1 Hz, 3H); 13 Ethyl O-Acetyl Acetohydroxamate (2d).…”

“…1 H NMR (400 MHz, CDCl 3 ) δ 8.06 (d, J = 8.2 Hz, 2H), 7.58 (t, J = 8.2 Hz, 1H), 7.46 (t, J = 7.3 Hz, 1H), 4.29 (q, J = 7.1 Hz, 2H), 2.16 (s, 3H), 1.36 (t, J = 7.1 Hz, 3H); 13 Ethyl O-Acetyl Acetohydroxamate (2d). 25 Colorless liquid (29.0 mmol scale, 3.86 g, 92%). 1 H NMR (CDCl 3, 400 MHz, ppm) δ 4.19 (q, J = 7.1, 2H), 2.15 (s, 3H), 2.04 (s, 3H), 1.32 (t, J = 7.1, 3H); 13 General Procedure for Amide Synthesis from Ketone.…”