Selektive Acylierungen von 3(5)‐Alkyl‐5(3)‐amino‐1H‐pyrazolen und eine neue Pyrazolo[5,1‐c]‐1,2,4‐triazol‐Synthese

Abstract

(allgemeine RegelnL41). Am Beispiel der Verbindung 3a konnte durch Rontgenstrukturanalyse gezeigt werden, da13 die Oxim-Gruppe uber eine intramolekulare WasserstoffBriicke stabilisiert in der 2-Konfiguration vorliegt. Intermolekulare Wasserstoff-Brucken in 3a zwischen dem Wasserstoff der OH-Gruppe und dem Stickstoff der 2-Position des Pyrazol-Ringes fuhren im kristallinen Zustand zur Ausbildung einer helicalen Uberstrukt~r [~~~].

The synthesis of novel hexa-13C-labelled glucosinolates from [13C6]-d-glucose

“…21 A more stable, colourless oil of 5a, which gradually solidified upon storage at room temperature, was thus obtained by simple work-up with water and extraction with diethyl ether. 22 To guarantee that no labelled material was wasted, the coupling reaction was carried out with an excess of the hydroximoyl chloride to maximise the conversion of the [ 13 C 6 ]thioglucose. The required 2,3,4,6-tetra-O-acetyl-b-D-gluconasturtiin (6a) was thus obtained in 88% yield.…”

“…13 22,23 The mixture was stirred at rt overnight before diluting with water and extracting with diethyl ether. The combined extracts were dried over MgSO 4 and the solvent was evaporated under reduced pressure to give a pale yellow oil of phenethylhydroximate chloride 5a (1.5 g, 100%).…”

Structure of the acylation products from 3,6-disubstituted and 3,6,7-trisubstituted 1H-pyrazolo[5,1-c] [1,2,4]triazoles

“…However, their chemistry is under-represented in the literature [8][9][10][11][12] , except perhaps in relation to 3,6,7-trisubstitutedpyrazolo [5,1- 13,14 In these reports, acetylation of 3,6-disubstituted-1H-pyrazolo [5,1-c] [1,2,4]triazole 1d to form the diacetylated compound 4d, together with the monoacetylated compound 5d, has been presented. 15 The formation of monoacetylated compounds 5e,f in the reactions of 6-methyl-7,8-dihydro-9H-1,3,4-triazolo [4,3-b][1,2,4]triazepin-8-ones 6e,f with acetic anhydride also has been described (Scheme 1).…”

Synthesis and chemistry of 3-tert-butyl-1,5-diaminopyrazoleCCDC reference number 211651. See http://www.rsc.org/suppdata/ob/b3/b306058f/ for crystallographic data in .cif or other electronic format.

“…In one other example of a 5-substituent directing the nucleophilic reactivity towards the 2-heteroatom in 3-aminopyrazole systems, a bulky tert-butyl group is apparently unnecessary. 4 Next, it was important to develop conditions which would allow the N-amination process to be driven to completion, since separation of 11-13 by Kugelrohr distillation was ineffective and chromatography proved time-consuming and low-yielding. Use of two equivalents of aminating agent gave an increased amount of products but starting material was still present; the situation was not improved by use of three or four equivalents of reagent which led to the presence of impurities in the final product.…”