New synthesis of 5-amino-5-deazaflavin derivatives by direct coupling of 5-deazaflavins and amines

5-Amino-5-deazaflavin derivatives are newly synthesized by direct coupling of 5-deazaflavins and amines. Some of them revealed potential activity toward tumor cells such as L1210 or KB cells.     

The photoreduction of 8-substituted 5-deazaflavins and the 5-deazaflavin catalyzed photoreduction of methyl viologen

Prolonged illumination of 8-X-5-deazaflavins (X = C1, N(CH₃)₂, NH₂, p-NH₂-C₆H₄) in the presence of an electron donor leads to the formation of a 5,5′-dimer and/or a 6,7-dihydro compound. The course and rate of these photoreductions were established and discussed in terms of electronic and steric effects, exerted by the substituent at position 8 and the electron donor. Pseudo first-order kinetics were found to apply to the photoreduction of 8-X-5-deazaflavins (X = Cl, NH₂, p-NH₂-C₆H₄) while the rate of the photoreduction of 8-X-5-deazaflavin (X = N(CH₃)₂) appeared to contain an autocatalytic element. The catalytic effect of 8-X-5-deazaflavins in the photoreduction of methyl viologen by EDTA was investigated. The substituent effect on the rate of the 8-X-5-deazaflavin mediated photoreduction of methyl viologen by EDTA was found to be comparable with that on the photoreduction rate of 8-X-5-deazaflavin in the presence of EDTA with the exception of 8-X-5-deazaflavin (X = N(CH₃)₂), which showed a remarkable relative enhancement of the reactivity towards methyl viologen photoreduction.     

The catalytic hydrogenolysis of benzylamine derivatives

The hydrogenolysis of optically active ethyl 2-amino-2-phenylpropionate (I), its N-methyl (II), and N,N-dimethyl (III) derivatives was studied using Raney Ni and Pd as the catalysts. The Raney Ni catalysed hydrogenolysis of II and III, as well as the reaction catalysed by Pd, occurred predominantly with inversion of configuration; this is not in accord with the hydrogenolysis of corresponding benzyl alcohols. This difference can be ascribed to the difference of the affinity for Ni between N and O atoms. The “SN_Ni” process may be inhibited in the Raney Ni catalysed hydrogenolysis of II and III since the amino group acts as a self-catalyst poison, and the “S_N2” process appears to be preferable to the “S_Ni” one. The predominance of the configurationally inversion was also observed in the Pd catalysed hydrogenolysis of I. These results over Pd are reasonable in reflecting that the N atom has not so high affinity for Pd. The hydrogenolysis of a quarternary ammonium bromide of I was also reported.     

Preparation of chiral 5-deazaflavin derivatives and their asymmetric reduction of ethyl benzoylformate

1,5-Dihydro-5-deazaflavin derivatives possessing a chiral substituent at N(3) position were synthesized, with which moderate asymmetric induction was observed in the reduction of ethyl benzoylformate.     

Synthesis of 8-demethyl-8-hydroxy-5-deazariboflavins

1-Deoxy 1-(3,4-dihydro-8-hydroxy-2,4-dioxopyrimido[4,5-b]quinolin-10-(2H)-yl)-D-ribitol (7,8-didemethyl-8-hydroxy-5-deazariboflavin), the flavin moiety of Methanobacterium coenzyme F₄₂₀, and its 7-methyl analog were prepared by acid-catalyzed reaction of appropriately substituted 6-(N-D-ribitylanilino)uracils with trimethyl or triethyl orthoformate followed by deprotection.     

Preparation of derivatives of 5-,6-, and 8-hydroxy-2-aminoanthracene

Three phenolic derivatives of 2-aminoanthracene have been prepared as their diacetyl derivatives by Bucherer-type amination of appropriately substituted anthracenes.     

Indirect electrochemical oxidation of benzylamine using 5-amino-6-hydroxy-2,4(1H, 3H)-pyrimidinedione as a current mediator

In the electrochemical oxidation of benzylamine on a Pt electrode at 15–35°C and pH 9.2, 5-amino-6-hydroxy-2,4(1H, 3H)-pyrimidinedione (uramil) was found to be utilized as a current mediator. The oxidized forms of uramil, which attack benzylamine to give N-benzylidene, were assumed to be alloxane ketimine and/or a neutral radical of uramil on the basis of the results of coulometric and kinetic experiments.     

Synthesis and properties of 7-hydroxy-8-phenylxanthine and its derivatives. Disproportionation to derivatives of 8-phenylxanthine and 6-amino-5-nitrosouracil

8-Phenyl, 8-(p-methoxyphenyl) and 8-(p-chlorophenyl)-7-hydroxyxanthine were synthesized by ring closure of 6-amino-5-nitrosouracil with benzaldehyde, p-methoxybenzaldehyde and p-chlorobenzaldehyde, respectively. The disproportionation of these products to the corresponding 8-phenylxanthines and 6-amino-5-nitrosouracil was studied. The dependence of the rate of the reaction on the various substituents was studied. The disproportionation reaction is inhibited by the polarophilic ethyl acetylenedicarboxylate and enhanced by phosphate.     

462—Indirect electrochemical oxidation of benzylamine using 5-amino-6-hydroxy-2,4(1H, 3H)-pyrimidinedione as a current mediator

In the electrochemical oxidation of benzylamine on a Pt electrode at 15–35°C and pH 9.2, 5-amino-6-hydroxy-2,4(1H, 3H)-pyrimidinedione (uramil) was found to be utilized as a current mediator. The oxidized forms of uramil, which attack benzylamine to give N-benzylidene benzylamine. were assumed to be alloxane ketimine and/or a neutral radical of uramil on the basis of the results of coulometric and kinetic experiments.     

Mass spectrometry of benzylamines and benzylamine derivatives

The mass spectra of benzylamine, N-ethylbenzylamine, N,N-dimethylbenzylamine, p-methoxybenzylamine and 4-hydroxy-3-methoxybenzylamine, and their acetamide and trimethyl- silyl (TMS) derivatives have been recorded. Low and high resolution spectroscopy were employed in conjunction with ion kinetic energy (IKE) determinations to establish the empirical formulae of the fragment ions and their modes of fragmentation. In the case of the acetamide derivatives the acyl group is lost by acetoxy elimination giving rise to the [M — 1] ion of the parent amine which then undergoes fragmentation very similar to the original amine. The TMS derivatives present more complex fragmentation patterns which involve rearrangement of the TMS side chain during decomposition. Consequently the acetamide derivative of an unknown aromatic amine is preferred for diagnostic purposes.     

Highly efficient oxidation of 2-imidazoline-5-carboxylic derivatives to imidazole-5-carboxylic derivatives by dioxygen

A highly efficient and environmental-benign oxidation by dioxygen (or air) as the sole oxidant was first applied for the conversion of 2-imidazoline-5-carboxylic derivatives to imidazole-5-carboxylic derivatives in very good and excellent yields. The substituent effect on 2-imidazoline ring was investigated. This protocol was also suitable for the synthesis of 2-imidazoles in relatively large scale.     

Solvent effects in 5-deazaflavin oxidation as a model for NAD+ dependent enzymes

The oxidation rate of 3,5-di-t-butylsalicyl alcohol by 3-methyl-10-ethyl-5-deazaisoalloxazine was found to be very sensitive to solvent effect, the rate constant in 99 vol% DMF being greater by a factor of 37 than that in 50:50 (v/v) DMF-water mixed solvent. The result suggests the importance of the aprotic nature of the reaction environment during the oxidation of alcohols by NAD⁺.     

Enzymatic resolution of 5-hydroxy- and 8-hydroxy-2-tetralols using immobilized lipases

(R)-2-Tetralol (R)-2a, (R)-5-hydroxy-2-tetralol (R)-2b and (R)-8-hydroxy-2-tetralol (R)-2c, which are key intermediates in the synthesis of pharmacologically active 2-aminotetralins 3, were prepared in moderate to very high enantiomeric excess (up to 99% ee) by enzymatic resolution of the corresponding racemic butyrates rac-1a, rac-1b and rac-1c, respectively, using lipases immobilized on octyl agarose. This methodology is an alternative to the microbial reduction of 2-tetralones.     

Characterization of 5-hydroxy-8-oxo-7,8-dihydroguanosine in the photosensitized oxidation of 8-oxo-7,8-dihydroguanosine and its rearrangement to spiroiminodihydantoin

The photosensitized oxidation of 2',3',5'-tris-(O-tert-butyldimethylsilyl)-8-oxo-7,8-dihydroguanosine (8-oxoG) with singlet oxygen was studied by low-temperature NMR. A stable intermediate was characterized at -60 degrees C by (13)C, 2D NMR HMBC spectra, and chemical shifts calculated by hybrid Hartree-Fock density functional theory which agreed with the structure 5-hydroperoxy-8-oxo-7,8-dihydroguanosine. Reduction of this intermediate at low temperature afforded the corresponding alcohol, the long-postulated 5-hydroxy-8-oxo-7,8-dihydroguanosine, the last intermediate in the formation of spiroiminodihydantoin. Upon warming to room temperature, this alcohol rearranges to form the spiroiminodihydantoin in good yield within 2 h.     

Acetylation of 8-Bromo-5-hydroxy-6,7,4′-trimethoxyflavone

5-Hydroxy-6,7,4′-trimethoxyflavone was isolated from Centaurea pseudomaculosa Dobrocz., and its bromo derivative was obtained. The reaction of 8-bromo-5-hydroxy-6,7,4′-trimethoxyflavone with acetic anhydride in the presence of a catalytic amount of p-toluenesulfonic acid gave of a 73% 5-acetoxy-8-bromo derivative whose structure was established by X-ray diffraction.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 999–1001.Original Russian Text Copyright © 2005 by Donbaeva, Yamovoi, Tuleuvov, Turdybekov, Gatilov, Adekenov.     

The synthesis of 8-hydroxy- and 8-methoxy-ellipticines

The first synthesis of 8-hydroxyellipticine is described and its identity with an ellipticine metabolite from $\text{Aspergillus}$$\text{alliaceus}$ confirmed.     

氮掺杂氧化石墨催化苄胺氧化

酰胺类化合物是重要的化工原料和生物医药合成的中间体,但其制备大部分需要使用贵金属催化剂,因此,发展廉价金属乃至非金属催化剂具有重大意义.本文使用化学气相沉积法合成了氮掺杂的层状氧化石墨材料,并将其应用于苄胺氧化反应中,实现了液相中酰胺合成的非金属催化过程.在水相中可以活化氧气较高产率地生成亚胺化合物N-苄亚甲基苄胺,并且成功实现了在氨水反应介质中高转化率和选择性地生成苯甲酰胺.此外,对反应中的影响因素进行了逐一研究,并从多方面探究了该反应中氨水的作用以及反应最可能的历程,提出了一条经过包括亚胺在内的多个中间产物的反应路径.本工作对于研究碳氢键的活化过程以及拓宽碳催化领域进行了有益的尝试.     

ortho-Selective metalation and electrophilic substitution of benzylamine derivatives

N-Pivaloylbenzylamines and derivatives thereof undergo smooth ortho-metalation when treated with two equivalents of an organolithium reagent. Subsequent carboxylation or hydroxylation lead to a variety of new products.