Imidazoline cycle

The formation of imidazoquinoxalines apparently proceeds through the tautomeric form D formed at the first stage of the reaction of the bases of Schiff C in which nucleophilic attack of atom N4 on the imine atom of carbon occurs with the closure of the imidazoline cycle the aromatization of which when exposed to the DMSO or oxygen of the air leads to the imidazo[l,5-fl]quinoxalin-4-one derivatives. 

Carlson, 1939 Murman, 1957) and then reacted with ketones in the presence of catalytic quantities of acids (Volodarsky et a/., 1977). In this case it is possible to introduce various alkyl groups into position 2 of the imidazoline cycle and synthesize spiro derivatives. 

Estimating the potential of the mass spectrometry method for the analysis of stable nitroxides and their precursors in the series of penta-substituted 3-imidazoline, it is possible to emphasize two main points. In the first place, the compositions of molecular ions, characteristic fragmentation ions, and losses make it possible to determine the compositions of substituents at all the carbon atoms of the imidazoline cycle (only in the case of AT -oxides are the overall values of the substituents R, and R obtained rather than complete information). In the second place, the... 

The postulated catalytic cycle is shown in Scheme 9.19. The N-heterocyclic carbene catalyst 11 (l,3-dimesityl-imidazolin-2-ylidene, IMes) attacks the a,/ -unsaturated aldehyde 62, generating the zwitterionic substance 66. After... 

Description. Heterocyclic quaternaries are derived from heterocyclic aliphatic or aromatic compounds in which a nitrogen atom constitutive of the cycle is quatemized. The precursors of such surfactants are heterocyclic molecules such as morpholine, imidazoline, pyridine, or isoquinoline. 

Treatment of l-hydroxy-3-imidazoline-3-oxides (6a,c) with Grignard reagent opens the cycle and forms 1,2-iV-t rt-butylhydroxylaminooximes (38a,c). Oxidation of the latter leads to acyclic stable nitroxides (39a,c)... 

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