Derivatives flavazole

The flavazoles, an interesting type of pyrazoline derivative obtained by interacting sugar quinoxalines with phenylhydrazine, will be discussed in the next Section (see p. 398). 

The synthesis of a series of l//-pyrazolo[3,4-3]quinoxalines (flavazoles) 55 by acylation, alkylation, halogenation, and aminomethylation of the parent compound was reported and their structures were investigated by H, and N NMR spectroscopy <2005T2373>. Restricted rotation about the partial C-N double bond of the A -acyl derivatives was studied by dynamic NMR spectroscopy and the barriers to rotation were determined. N NMR data of a series of 3-alkyl [aryl]-substituted 5-trichloromethyl-l,2-dimethyl-l//-pyrazolium chlorides 56 (where the 3-substituents are H, Me, Et, -Pr, -Bu, -Pent, -Hex, (CH2)sC02Et, CH2Br, Ph, and 4-Br-C6H4) were reported <2002MRC182>. The N substituent chemical shift (SCS) parameters were determined and these data were compared with the SCS values and data obtained by molecular orbital (MO) calculations. 

In alcoholic solution, lactose reacts with ammonia, aniline, do-decylamine, urea, guanidine, and hydroxylamine, respectively, to give lactosylamine derivatives. W-Octadecyllactosylamine was formed by condensing octadecylamine with lactose in 2-propanol-water (5 3 vol./ vol.) at room temperature. Occasionally, presence of a trace of acidic catalyst, such as ammonium chloride, zinc chloride, or hydrogen chloride may be necessary, especially if the amine is a weak base. p-Amino-phenol and p-phenetidine condense with lactose under such conditions. Condensation of lactose with o-phenylenediamine gives a quinoxaline (41), which is transformed into a flavazole derivative (42) on reaction with phenylhydrazine. The existence of a molecular compound of lactose with... 

The term C-nucleoside was only coined after isolation and characterization of the first member of this class pseudouridine, in 1975 [97ACH(ip)]. Before that, alditolyl derivatives of some heterocycles (acyclo C-nucleo-sides) were known both as natural products (alditolyl pteridines or biopterins) as well as products of syntheses (e.g., alditolyl derivatives of imidazoles, benzimidazoles, thiazoles, benzothiazoles, 1,2,3-triazoles, quinoxalines, and flavazoles) and were classified as carbohydrate derivatives of heterocyclic compounds. After isolation of pseudouridine, other naturally occurring members were successively isolated, characterized, and synthesized. It is worth mentioning that synthesis preceded isolation in two cases 9-dea-zaadenosine and pyrrolosine. Comparison with the synthetic compounds facilitated structure elucidation in one case (9-deazaadenosine) and structure reassignment in the other (pyrrolosine). 

Pyrazolo[3,4-f ]quinoxalines (flavazoles) (e.g., 10) are formed by the reaction of 2-polyhydroxyalkylquinoxalines with hydrazines. Thus with phenylhydrazine, 1-phenyl derivatives are formed and with hydrazine itself, the 1-unsubstituted compounds are obtained. Starting with a 2-D-arabinotetrahydroxybutyl compound, a 3-(D-erythrotrihydroxy-propyl)flavazole is obtained. ... 

Many standard reactions of sugar derivatives have been performed on 1-phenylflavazoles derived from reducing sugars. For example, glycosidic links in flavazoles derived from disaccharides are readily hydrolyzed with... 

Benzoyl-2-oxo-l,2-dihydroquinoxaline hydrazones and flavazoles derived therefrom. Russ J Org Chem 39(1) 131-140. doi 10.1023/A 1023415301274... 

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