Catalytic phosphorylation using a bifunctional imidazole derived nucleophilic catalyst

A bifunctional catalyst containing a polyether backbone and a nucleophilic imidazole moiety has been prepared that demonstrates cooperative catalysis in the presence of added group 1 and 2 salts for the phosphorylation of alcohols.     

Nucleophilic behavior of DBU in a conjugate addition reaction

Reaction of DBU with a diarylpyrone results in 1,4 addition of the DBU and subsequent fragmentation of the DBU moiety into an aminopropyl caprolactam. Incorporation of the fragmented DBU into the diarylpyridone is postulated to occur by an addition/elimination pathway.     

Novel carbohydrate-based bifunctional organocatalysts for nucleophilic addition to nitroolefins and imines

Glucosamine has been selected as a cheap and readily available chiral scaffold for the synthesis of a series of novel enantiomerically pure bifunctional organocatalysts bearing a tertiary amino group in proximity to a (thio)urea group. The catalytic behaviour of these compounds, both as neutral and N-protonated species, was investigated using the addition of acetylacetone to β-nitrostyrene as a model reaction. Under optimized experimental conditions, chemical yields up to 93% and enantioselectivities up to 89% were obtained. Semiempirical (AM1) computational studies allowed to find a theoretical rationale for the chemical and stereochemical behaviour of the catalyst of choice. These catalysts were also preliminarily investigated as promoters in the addition of diethyl malonate to the N-Boc imine of benzaldehyde, affording the product in up to 81% ee.     

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.     

Functionalisation of fluorescent BODIPY dyes by nucleophilic substitution

The BODIPY chromophore can be easily modified by nucleophilic mono- or disubstitution of 3,5-dichloroBODIPY with O-, N-, S- and C-nucleophiles. Absorption and fluorescence spectral data of the new BODIPY derivatives are also reported.     

Synthesis,DFT calculations,cyclic voltammetry and antibacterial activities of a new blue-violet dye and a new blue-green fluorescent heterocyclic system

The new blue-violet dye 2-(3-hydroxyimino-2,3-dihydroimidazo[1,2-a]pyridin-2-yliden)-2-(2-thienyl)acetonitrile was prepared in high yield from the reaction of 3-nitroimidazo[1,2-a]pyridine with 2-(2-thienyl)acetonitrile by nucleophilic substitution of hydrogen. Acylation of the hydroxyl group led to a new heterocyclic system, (pyrido[2′,1′:2,3] imidazo[4,5-b]thieno[2,3-e]pyridine-11-carbonitrile) with very strong blue-green fluorescent properties. Physical, spectral and analytical data have confirmed the structures of the synthesized dyes. The optical and solvatochromic properties of these compounds were investigated and showed interesting photophysical properties. Density functional theory calculations of blue-violet and fluorescent dyes were performed to provide the optimized geometries, Mulliken atomic charges, relevant frontier orbitals and the prediction of ¹H NMR chemical shifts. The electrochemical properties of these dyes were investigated by cyclic voltammetry and an oxidation wave was observed at a half-wave potential of −0.143 V versus SCE for the blue-violet dye. Also, these new compounds exhibited potent antibacterial activity against Gram positive and negative bacterial species.     

Synthesis and photophysical characterization of new fluorescent bis-amino acids bearing a heterocyclic bridge containing benzoxazole and thiophene

A series of new bis-alanine derivatives bearing (oligo)thiophene and benzoxazole units as the heteroaromatic bridge were synthesized in moderate to good yields. The photophysical characterization of these bis-amino acids was performed by UV-vis absorption and fluorescence emission studies and revealed that the compounds displayed exceptionally high fluorescence quantum yields, making them good candidates for application as fluorescent probes when incorporated into peptides, as well as peptide conformation-restricting and cross-linking elements.     

Reaction of heterocyclic betaines. Synthesis of a new heterocyclic system

A new condensed heterocyclic system, viz., 1,3,7,9-tetra-oxo-2,8-diphenyl-6-formylpyrimido [3,4-a]pyrimido[4,5-dloxazine, was synthesized, and its electronic and PMR spectra were recorded. Factors that affect the orientation of nucleophilic substitution in betaines of the pyrimidine series with aliphatic amines are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 993–995, July, 1980.     

Enantioselective heterocyclic synthesis of spiro chromanone-thiochroman complexes catalyzed by a bifunctional indane catalyst

Novel asymmetric domino reactions of benzylidenechroman-4-ones and 2-mercaptobenzaldehydes for efficient construction of spiro chromanone-thiochroman complexes were accomplished with high yields and excellent selectivities via a novel bifunctional indane catalyst.     

An efficient one‐pot synthesis of a new heterocyclic system with high‐fluorescent properties

Nucleophilic substitution of hydrogen in nitro derivative of imidazo[1,2‐a]pyridine has been used as a key step in the one‐pot synthesis of a new highly fluorescent heterocyclic system pyrido [1″,2″:1′,2′]imidazo[4′,5′:5,6]pyrido[2,3‐b]indole. J. Heterocyclic Chem., (2012).     

Synthesis of heterocyclic compounds via nucleophilic aroylation catalyzed by imidazolidenyl carbene

Xanthones and acridones were synthesized from 3,4-difluoronitrobenzene and 2-fluorobenzaldehydes in two or three steps. The key step was nucleophilic aroylation catalyzed by imidazolidenyl carbene. The nucleophilic aroylation of 3,4-difluoronitrobenzene afforded 2,2'-difluoro-4-nitrobenzophenones. The cyclization of the difluorobenzophenones with O-nucleophile and N-nucleophile yielded 3-nitroxanthones and 3-nitroacridones, respectively. Indazole, quinolino[2,3-b]quinoxaline, and thianaphtho[2,3-b]quinoxaline derivatives were also synthesized via nucleophilic aroylation of 2,3-dichloroquinoxaline followed by cyclization with nucleophiles.     

Water-soluble oligomer dimers based on paracyclophane: a new optical platform for fluorescent sensor applications

Water soluble paracyclophane chromophore dimers provide optical reporters that show little sensitivity to surfactants and thus are ideal for biosensor design. Strong intramolecular delocalization circumvents complications from intermolecular delocalization in spontaneously formed aggregates. The synthesis of 2 involves a novel TBAT deprotection/butane sultone ring-opening sequence, which should be general for the preparation of water-soluble conjugated oligomers and polymers.     

Orthogonally reactive SAMs as a general platform for bifunctional silica surfaces

We report the synthesis and self-assembly of azide and amine trimethoxysilanes that result in mixed monolayers on silica. The amine and azide functional groups can be independently reacted with acid chlorides and terminal alkynes, respectively. Consequently, these orthogonally reactive monolayers represent a general starting point for making bifunctional surfaces. Using X-ray photoelectron spectroscopy, we determined the azide/amine surface ratio as well as the reactivity of the azide and amine functional groups in the mixed self-assembled monolayer (SAM). Significantly, the surface azide/amine ratio was much lower than the azide/amine ratio in the self-assembly mixture. After determining the self-assembly mixture composition that would afford 1:1 azide-amine mixed monolayers, we demonstrated their subsequent functionalization. The resulting bifunctional surface has a similar functional group ratio to the azide/amine precursor SAM demonstrating the generality of this approach.     

Catalytic nucleophilic activation of acetonitrile via a cooperative catalysis of cationic Ru complex, DBU, and NaPF6

The development of an efficient catalytic system for the direct addition of acetonitrile under mild amine basic conditions is described. A cooperative catalysis of CpRu complex, DBU, and NaPF₆ enables chemoselective and catalytic generation of nucleophiles from barely acidic acetonitrile, which is integrated into the addition to aldehydes, imines, and activated ketones. Mechanistic investigations revealed that the three catalyst components work together to achieve high catalytic efficiency.     

Two new fluorescent heterocyclic perimidines: first syntheses, crystal structure, and spectral characterization

An efficient one-pot synthesis of two new heterocyclic perimidines 4-(2,3-dihydro-1H-perimidin-2-yl)-2-methoxyphenol and 2-(quinoxalin-2-yl)-2,3-dihydro-1H-perimidine in good yields is presented. This methodology provides a simple, straightforward synthetic route to these interesting classes of heterocycles. Crystal structure, solvatochromism, and antibacterial activity of these organic compounds are discussed.     

Synthesis of hydrogenated heterocyclic compounds by the addition of nucleophilic reagents to semicyclic α-methenyl 1,5-diketones

The addition of primary and secondary amines and hydrogen cyanide to semicyclic -methenyl 1,5-diketones of the 1,3-diphenyl-1-(2-oxocyclohexyl)-2-methenyl-3-propanone type leads, respectively, to compounds with hydrogenated quinoline, -flavenone, and chroman structures.Communication XXIV from the series Reactions of 1,5-Diketones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1356–1360, October, 1977.