Structure of the diazonium coupling products of .gamma.-phenyl-.DELTA..beta.,.gamma.-butenolide

Abstract

the 355-Hz band disappears on the addition of D20. Triphenylamine was used as obtained from Eastman Chemicals (Amx 298 nm, t 22.3 X lo3 in CH3CN).Elemental analyses for the compounds in the experimental section were submitted for review and are in agreement with theoretical values.Preparation of the ?r Complexes. Method A. A hot solution of 2.5 X mol of the pyrylium salt in 20 ml of acetonitrile was added to a hot solution of 2.5 X mol of V in 30 ml of acetonitrile. On cooling, the complex separates in pure form. It may be crystallized from acetonitrile.

Some reactions with ω‐bromoacetophenone: Synthesis of Δαβ‐butenolide and its transformation into pyrrole derivatives

“…Based on these data as well as on elemental analyses (Table I), the other possibility of cyclization of the intermediate 5 into 7 was ruled out. A similar behavior of butenolides has been previously reported [9].…”

Convenient synthesis of some new substituted pyrazolyl-1,3,4-oxadiazoles and pyrazolyl-1,2,4-triazoles

“…Treatment of 5-aryl-3H-furan-2-ones (2a,b) [33,35] (formed in situ by cyclization of 4-oxo-4-arylbutyric acid 1 by the action of acetic anhydride-sulfuric acid mixture) with aromatic diazonium salts, afforded colored products that were identified as 3-arylhydrazono-5-aryl-3H-furan-2-one derivatives (3a,b). The structures of the latter products were confirmed by the appearance of hydrazone NH and carbonyl bands near 3280 and 1750 cm -1 , respectively in their IR spectra and the lack of the characteristic signals due to methylene protons in their 1 H NMR spectra.…”

“…Elemental analyses were carried out at the Microanalytical Center of Cairo University. 5-Aryl-3H-furan-2-ones (2a,b) were prepared according to literature procedure [33,35].…”

“…After complete addition, the reaction mixture was allowed to stand overnight on a refrigerator and the precipitated solid was collected by filtration, washed with water and finally crystallized from ethanol/DMF to afford the corresponding hydrazone derivatives (3a,b). General Procedure: To the appropriate 5-aryl-3H-furan-2-one (2) [33,35] (10 mmol) (prepared in situ according to procedure A above) was added the appropriate N-nitrosoacylarylamine (10 mmol) [34,35]. The reaction mixture was shaken to effect complete dissolution of the reactants and then left to stand overnight at room temperature.…”

13C and 1H NMR study of azo coupling products from diazonium salts and furan‐2‐(3H)‐ones

“…The authors have proposed three possible tautomeric forms, and on the basis of elemental analysis and spectroscopic methods have indicated formation of hydrazones furanone series. According to the authors, their stabilization is possible with the participation of the intramolecular hydrogen bond that is formed between the CO and NH groups . However, these data are insufficient to accurately determine the structure of the compounds studied.…”