Influence of substituents structure and their electronic effects on acid-base and complexing properties of 5,10,15,20-tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin

5,10,15,20-Tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin has been prepared, and its acid-basic properties have been studied in acetonitrile by titration with 1,8-diazabicyclo [5.4.0]undec-7-ene and perchloric acid. The substituted porphyrin ability towards complex formation with zinc acetate has been studied in acetonitrile and acetonitrile, 1,8-diazabicyclo [5.4.0]undec-7-ene media. Spectral properties of neutral and ionic forms of 5,10,15,20-tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin and its zinc complex have been determined; constants of acid and basic ionization of the ligand have been estimated. Kinetic parameters of the porphyrin complex formation with zinc via molecular and ionic mechanism have been analyzed. The substituents effect on the studied properties is discussed.     

Spectrophotometric study of 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin in the system 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile at 298 K. Deprotonation of the pyrrole rings and complex formation with Zn(OAc)2

Acid-base and complexing properties of 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin in the system 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile were studied at 298 K by spectrophotometric titration. The titration of 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with 1,8-diazabicyclo[5.4.0]-undec-7-ene was accompanied by successive deprotonation of the pyrrole nitrogen atoms with formation of the corresponding mono- and dianions, and the acid dissociation constants were determined. Complex formation of doubly deprotonated 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with zinc acetate was studied.     

Synthesis and spectrophotometric study of the acid-base and complexing properties of 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin in acetonitrile

2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin has been synthesized, and its acid-base and complexing properties in the systems 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile, acetonitrile-Zn(OAc)₂, and 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile-Zn(OAc)₂ have been studied by spectrophotometry. Titration of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin with 1,8-diazabicyclo[5.4.0]undec-7-ene is accompanied by successive deprotonation of the pyrrole nitrogen atoms with formation of the corresponding mono- and dianion. The overall acid dissociation constant of the title compound has been determined. The complexation of neutral and doubly deprotonated 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin with Zn(OAc)₂ has been studied, and kinetic parameters for the formation of the zinc complex according to the molecular and ionic mechanisms have been determined. Extra coordination of 1,8-diazabicyclo[5.4.0]undec-7-ene by the zinc complex of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin.     

Synthesis and spectrophotometry study of the acid-base properties of nitro-substituted 5-phenyl-β-octaalkylporphines

10,15-Dinitro-5-phenyl-2,3,7,8,12,13,17,18-octamethylporphine, 10,15,20-trinitro-5-phenyl-2,3,7,8,12,13,17,18-octamethylporphine, and 10,15,20-trinitro-5-(4-nitrophenyl)-2,3,7,8,12,13,17,18-octamethylporphine were synthesized and identified by electronic absorption, IR, and ¹Н NMR spectroscopy. The acid–base properties of the synthesized compounds were studied by spectrophotometric titration in HClO₄–acetonitrile and 1,8-diazabicyclo[5.4.0]undec-7-ene–acetonitrile systems at 298 K. Parameters of the electronic absorption spectra and concentration ranges of existence of the mono- and diprotonated, as well as mono- and dideprotonated forms of the corresponding ligands and the acid and base dissociation constants of the latter were determined. Comparative analysis of the effect of nitro groups on the reactivity of the synthesized compounds was performed.     

Spectrophotometric study of acid-base and complexing properties of 5,10,15-trinitro-2,3,7,8,12,13,17,18-octaethylporphyrin in acetonitrile

Acid-base and complexing properties of 5,10,15-trinitro-2,3,7,8,12,13,17,18-octaethylporphyrin have been studied by means of spectrophotometry in the acetonitrile/1,8-diazabicyclo[5.4.0]undec-7-ene, acetonitrile/perchloric acid, and acetonitrile/zinc acetate media. The ionization constants and concentration ranges of ionized forms existence have been determined, spectral parameters of the studied porphyrin and its zinc complex have been elucidated, and kinetic parameters of the zinc complex formation have been analyzed.     

Study of acidity and coordination properties of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin in the system of 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile

Spectrophotometric titration method was used to study the acidic properties of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin in the presence of a deprotonated agent, 1,8-diazabicyclo[5.4.0] undec-7-ene, in acetonitrile. The spectral characteristics of the ionized forms and combined ionization constant for the first and second stages were revealed. The reaction of complex formation between the dianionic forms of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin and zinc acetate was studied.     

Preparation and characterization of 6-substituted 1,8-diazabicyclo[5.4.0]undec-7-ene

The lithium 1,8-diazabicyclo[5.4.0]undec-6-ide ( 1 ) prepared from 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and n-butyllithium reacts with alkyl halides and carbonyl compounds such as benzophenone, acetophenone, and benzaldehyde to give 6-substituted DBU derivatives in good yields. The reaction behavior of 6-substi-tuted DBU was also investigated.     

Silver(I) Oxide-/DBU-Promoted Synthesis of Dihydrofuran Units through Allenyl Silver Formation

A formal [3+2] cyclization mediated by silver(I) oxide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is described herein. Through a broad variety of carbonyl compounds, this system can promote cyclization reactions with high yield (up to 85 %) and diastereoselectivity (up to 95:5) for a straightforward access to complex and congested dihydrofuran derivatives in one step under mild conditions. Based on DFT studies, the proposed mechanism would involve an allenyl silver intermediate.     

Bis(4-nitrophenyl)phosphorylazide as a reagent for direct azidation of polyfunctional derivatives of pyrimidin-4(3<Emphasis Type="Italic">Н</Emphasis>)-one

The application of bis-(4-nitrophenyl)phosphorylazide–1,8-diazabicyclo[5.4.0]undec-7-ene system for direct transformation of polyfunctional derivatives of pyrimidin-4(3H)-one in the corresponding 4-azidopyrimidines has been suggested for the first time. Using this system, novel 4-azido-6-(2,6-dihalo-α-methoxybenzyl)-5-methyl-2-(nitroamino)pyrimidines have been obtained in good yield under mild conditions.     

Palladium-catalysed dimerization of isoprene with carbon dioxide in the presence of organotin ethoxide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)

The palladium-catalysed dimerization of isoprene with carbon dioxide is promoted by treatment wiht tributyltin ethoxide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).     

Trifluoromethanesulfonate,trifluromethylsulfonylimide, and bis(trifluoromethylsulfonyl)imide salts and ionic liquids based on 1,8-diazabicyclo[5.4.0]undec-7-ene and 1,5-diazabicyclo[ 4.3.0]non-5-ene

Trifluoromethanesulfonate, trifluoromethylsulfonylimide, and bis(trifluoromethylsulfonyl)imide salts and ionic liquids were synthesized from 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine (1,8-diazabicyclo[5.4.0]undec-7-ene) and 2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidine (1,5-diazabicyclo[4.3.0]non-5-ene). Their physicochemical properties, spectral parameters, and some chemical transformations were studied.     

Synthesis of 4-phenyloxazinones via DBU-catalyzed cleavage of 4-bromomethylcoumarins

A new route for ring transformation has been discovered during the reaction of 4-bromomethylcoumarins with hydroxyl amine in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), leading to the formation of pharmacologically important 1,2-oxazinones in a single step with very high yields.     

Synthesis and spectrophotometric study of deprotonation of octamethylporphyrin derivatives with 1,8-diazabicyclo[5.4.0]undec-7-ene in acetonitrile

Acidic properties of synthesized 5,10,15,20-tetrakis(4′-tert-butylphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin and 5,10,15,20-tetrakis(3′,5′-di-tert-butylphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin have been studied by spectrophotometry. Deprotonation of the intracyclic nitrogen atoms with 1.8-diazabicyclo [5.4.0]undec-7-ene in acetonitrile occurs in two steps. Deprotonation constants and ranges of the porphyrinsanionic forms existence have been determined, and influence of the peripheral substituents on acidic properties of the macrocyclic ligand has been elucidated.     

Cycloadducts of methyl hydroxyalkynoates and DBU: Transformation into tethered furan-2(5H)-one and caprolactam structures

Russian Journal of Organic Chemistry - Cycloadducts of 1,8-diazabicyclo[5.4.0]undec-7-ene and methyl 4-hydroxyalk-2-ynoates, octahydro-5H,9H-[1,3]oxazolo[2′,3′:...     

New one-pot synthesis of pyrazole-5-carboxylates by 1,3-dipole cycloadditions of ethyl diazoacetate with α-methylene carbonyl compounds

A facile one-pot procedure for the synthesis of pyrazole-5-carboxylates by 1,3-dipolar cycloaddition of ethyl diazoacetate is described. Cycloadditions with α-methylene carbonyl compounds utilizing 1,8-diazabicyclo[5.4.0]undec-7-ene as base and acetonitrile as solvent provide pyrazoles with excellent regioselectivity and good yields. The reaction was found to proceed by a domino 1,3-dipolar cycloaddition-water elimination.     

Synthesis of 2-mercaptobenzothiazoles via DBU-promoted tandem reaction of o-haloanilines and carbon disulfide

An efficient strategy for the synthesis of a variety of 2-mercaptobenzothiazole derivatives has been developed. The reaction proceeded from o-haloaniline derivatives and carbon disulfide via a tandem reaction in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to afford the corresponding 2-mercaptobenzothiazole derivatives in good to excellent yields.     

Spectrophotometric study of the complexing properties of 2,3,7,8,12,13,17,18-Octaethyl-5,10,15-trinitroporphyrin and its dianion toward Zn(OAc)2 in acetonitrile

Complexing properties of 2,3,7,8,12,13,17,18-octaethyl-5,10,15-trinitroporphyrin and its dianionic form in the systems acetonitrile-Zn(OAc)₂ and 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile-Zn(OAc)₂ have been studied by spectrophotometric titration. Zinc complexes of 2,3,7,8,12,13,17,18-octaethyl-5,10,15-trinitroporphyrin have been characterized by spectral data, and kinetic parameters of the complex formation according to the molecular and ionic mechanisms have been analyzed.     

Perfluoroalkanosulfonyl fluoride:A useful reagent for dehydration of aldoximes to nitriles

The reaction of a variety of aldoximes with perfluoroalkanosulfonyl fluoride in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU) in dichloromethane smoothly generated the corresponding nitriles in 70%–95% yields.     

Synthesis of onio-, dionio-, and trionio-substituted phosphines; the nucleophilic behavior of DBN and DBU toward main group electrophiles

1,5-Diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) react with chloro- and dichloro-phosphines leading to onio- and dionio-substituted phosphines. Similarly, onio-substituted silicon and tin derivatives are prepared; they are used as onio-substituent transfer reagents in the synthesis of a trionio-substituted phosphine.     

Unique cascade ring-opening/cyclization reaction of azlactones and DBU or DBN: Synthesis of new pyrrolam A analogues

1-Azabicyclo[3.3.0]oct-3-en-2-one derivatives were synthesized efficiently through the facile cascade reaction of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) with arylidene azlactones. This research provides a straightforward procedure for the synthesis of a novel class of multicyclic semi-alkaloids which shows good antimicrobial activity. Under catalyst-free, mild, and solventless condition, a wide range of fused tricyclic derivatives was obtained in high yields.