Synthesis, structure and electrochemical behaviour of 2,2-diferrocenylpropane-substituted dihydropyrazole derivatives

The reaction of α,β-unsaturated ketones of 2,2-diferrocenylpropane with hydrazine led to the formation of 2,2-diferrocenylpropane-substituted dihydropyrazole. The further reaction of dihydropyrazole with p-pyridinecarboxylic acid chloride or benzoyl chloride resulted in the isolation of two novel 2,2-diferrocenylpropane-substituted acyl dihydropyrazole derivatives. All of these compounds were analyzed by MS, IR and ¹H NMR spectra. The crystal structure of representative compound, 1-p-pyridine acyl-3-ferrocenyl-5-(2,2-diferrocenylpropane)-4,5-dihydropyrazole (5a) has been elucidated by X-ray diffraction. The electrochemical behaviours of all the compounds have been examined.     

Synthesis and study of water-soluble macroheterocycles based on cyclopenta[cd]phenalene with fragments of benzidine derivatives

Previously unknown arylenediamines and macrocyclic derivatives of cyclopenta[cd]phenalene with fragments of benzidine derivatives (3,3′-dichloro, 3,3′-dimethoxy, 2,2′-disulfo, 2,2′-dinitro) were prepared by the reaction of 2,6-dihydro-1H-cyclopenta[cd]phenalene-5,7-diimine with substituted diamines of the diaryl series. The IR and UV data for the new compounds are reported.     

The synthesis and structural characterisation of an homologous series of group 14 1-chloro-2,2-difluorovinyl compounds

A series of group 14 1-chloro-2,2-difluorovinyl compounds Ph₃E(CClCF₂) (E=Ge, Sn, Pb) has been prepared using the low temperature reactions of 1-chloro-2,2-difluorovinyllithium (LiCClCF₂), generated in situ from CF₃CH₂Cl (HCFC-133a) and n-butyllithium. These new materials have been fully characterised, including for E=Ge and Sn, by single crystal X-ray studies. This is the first time that any main-group 1-chloro-2,2-difluorovinyl compounds have been crystallographically studied.     

Acid-catalyzed condensation of 2,2′-diamino-1,1′-biaryls for the synthesis of benzo[c]carbazoles

2,2′-Diamino-1,1′-biaryls were found to undergo ring-closure condensation reaction to afford benzo[c]carbazoles in good to excellent yield. Coupled with the synthesis of 2,2′-biaryldiamines from diaryl hydrazides via [3,3]-sigmatropic rearrangement, it constitutes a new efficient synthetic method for benzo[c]carbazoles and related compounds.     

Photo-stabilization of cis-1,4-polybutadiene with phenylene sulphide oligomers

The new thiooligomers of hydroxyphenylene and hydroxymethoxyphenylene sulphides have been used as photo-stabilizers for cis-1,4-polybutadiene. The photo-stabilizing properties of these thiooligomers were compared with commercial sulphur-containing compounds such as bis(4-hydroxyphenylene)sulphide, 2,2′-thiobis(4-methyl-6-tert.butylphenol) (Irganox 1081), bis((beta-(3,5-di-tert,butyl-4-hydroxybenzyl)-methylcarboxyethyl))sulphide (Irganox 1035) and dilaurylthiodipropionate (Irganox PS800). The photo-stabilizing mechanisms of these compounds have been discussed in detail.     

1,3-Dipolar cycloaddition ofin situ generated 2,2-dimethyl-and 2,2-dichlorodiazocyclopropanes to 3,3-dimethylcyclopropene

2,2-Dimethyl- and 2,2-dichlorocyclopropyl-N-nitrosoureas were synthesized for the first time. Under the action of MeONa/MeOH at ?10°C, these compounds generate the corresponding 2,2-dimethyl- and 2,2-dichlorodiazocyclopropanes, which are readily trapped by 3,3-dimethylcyclopropene to give the products of 1,3-dipolar cycloaddition,viz., isomeric substituted spiro(2,3-diazabicyclo[3. 1 .0] hex-2-ene-4,1 ′-cyclopropanes), in yields of about 70%,     

A closer insight into the mechanism operating in the trifluoroacetylation of pyrrole. New trifluoromethyl pyrroylmethane discovered

A former studied reaction of acetylation of pyrrole was revisited and this allowed the identification of new compounds and the isolation and characterization of a very stable solid (2,2′,2″-(2,2,2-trifluoroethane-1,1,1-triyl)tris(1H-pyrrole)). All these materials were probably missed, buried in the black tar that characterizes the reaction. A careful and thorough selection of the reaction’s conditions provided both evidence for three new compounds and a closer insight into the mechanism operating at room and lower temperatures.     

Stereoselective synthesis of (E)-4-alkoxy-2-aryl-5-chloro-2-thiazolines

The first synthesis of the title compounds has been achieved starting from chloralamides by a route involving chemical and electrochemical steps. N-(1-Alkoxy-2,2,2-trichloroethyl)benzamides were efficiently prepared from chloralbenzamides and were electrochemically converted into N-(1-alkoxy-2,2-dichloroethyl)benzamides in high yields by cathodic reduction in a protic medium. Thionation of these compounds with Lawesson's reagent followed by basic treatment gave novel (E)-4-alkoxy-2-aryl-5-chloro-2-thiazolines in fair to quantitative yields.     

5-Amino-4-aryl-2,2-dimethyl-1,3-dioxans: application as chiral NMR shift reagents and derivatizing agents for acidic compounds

The use of (4S,5S)-5-amino-2,2-dimethyl-4-phenyl-1,3-dioxan (ADPD) and (4R,5R)-5-amino-(4′-biphenyl)-2,2-dimethyl-1,3-dioxan (ABDD) as chiral solvating agents (CSA) for the ee determination of compounds bearing an acidic proton by means of ¹H NMR spectroscopy is demonstrated. In addition, based on the well known rigid conformation of these amines, ADPD and ABDD are suitable as chiral derivatizing agents (CDAs) in order to determine absolute configurations.     

Molecular complexes of aryltellurium(IV) chlorides

The synthesis and spectroscopic study of molecular complexes of type [RTeCl₃ · L] and [RTeCl₃ · 2L], where R = phenyl, 4-phenoxyphenyl and L = pyridine, pyridine-N-oxide, tri-n-octylphosphine oxide, 1,10-phenanthroline and 2,2′-bipyridyl are reported. These compounds were characterised by their IR spectra, elemental analysis and conductivity data. The conductivities in acetonitrile shows the non-electrolytic behaviour of these hygroscopic compounds which are monomeric in boiling benzene.     

Synthesis of 8-R-9c-alkyl-1-aryl-2-benzyl-1-hydroxy-1,2,9b,9c-tetrahydro-5-oxa-2-aza-cyclopenta[2,3]cyclopropa[1,2-a]naphthalene-3,4-diones and reaction thereof with acetic anhydride

The reaction of zinc enolates synthesized from 1-aryl-2,2-dibromoalkanones and zinc with 6-R-2-oxochromene-3-carboxylic acid N-benzylamide affords 8-R-9c-alkyl-1-aryl-2-benzyl-1-hydroxy-1,2,9b,9c-tetrahydro-5-oxa-2-aza-cyclopenta[2,3]cyclopropa[1,2-a]naphthalene-3,4-diones. Acylation of these compounds is accompanied by an unexpected rearrangement producing a sole geometrical isomer of 4′-alkyl-5′-aryl-1′-benzyl-3,4,2′,3′-tetrahydro-2,2′-dioxospiro[chroman-3,3′-pyrrol]-4-yl acetates.     

Synthesis and characterization of a new trans-2,2′-azoquinoxaline bridged bisphthalocyanine

A new trans-2,2′-azoquinoxaline bridged bisphthalocyanine was synthesized from the corresponding quinoxaline-2(1H)-one oxime, which can be obtained by the reaction of s-trans-chloroethanedial with 2-(3,4-diaminophenoxy)-9,16,23-tri(hexylthio)phthalocyanine zinc(II). 2-(3,4-Diaminophenoxy)-9,16,23-tri(hexylthio)phthalocyanine zinc(II) was synthesized by reduction of 2-(4-amino-3-nitrophenoxy)-9,16,23-tri(hexylthio)phthalocyanine zinc(II). Novel compounds were characterized by elemental analysis, UV/vis, IR and ¹H NMR spectroscopy. The conductivity and the humidity sensing properties of spin coated films of these compounds were investigated by measuring the complex impedance spectra at different humidities. Films of the final product show up to 10³ orders of magnitude higher conductivity than the starting and intermediate compounds. The results indicate that the presence of water vapour always leads to a drop in the real and imaginary part of the complex impedance. At room temperature, the capacitance of the films exhibits reversible increase with relative humidity, which makes these films attractive for humidity sensing applications.     

Convenient syntheses of zero valent 2,2′-bipyridine and related complexes of transition metals

The neutral tris-2,2′-bipyridine(bipy) and 1,10-phenanthroline(phen)compounds Mbipy₃ and Mphen₃ can be made conveniently in high yield by sodium amalgam reduction of the chlorides of Ti, Zr, Hf, V, Nb, Ta, Cr or better, for Mo, W and Re, the respective adducts MoCl₄L, WCl₄L and ReCl₄(THF) in tetrahydrofuran containing the ligands. The Cr and Mo compounds can also be obtained from the dimeric acetates M₂(CO₂Me)₄. For vanadium, similar compounds have been obtained from 2,2′-dipyridylamine, 2,2′-dipyridyldisulfide and di-t-butyldiimine. Reduction of VCl₃ in THF containing one equivalent of 2,2′-bipyridine under CO gives the carbonyl V(CO)₄bipy. Interaction of Vbipy₃ with NO and CH₃I give respectively, V(NO)bipy₃ and [V(CH₃)I(bipy)].     

A novel ionic liquid mediated synthesis of 4(1H)-quinolones, 5H-thiazolo[3,2-a]pyrimidin-5-one and 4H-pyrimido[2,1-b]benzothiazol-4-ones

A new, convenient, environmentally benign two-step synthesis of 4(1H)-quinolones, 5H-thiazolo[3,2-a]pyrimidin-5-one and 4H-pyrimido[2,1-b]benzothiazol-4-ones have been developed by first condensing substituted arylamine/2-aminothiazole/2-aminobenzenethiazole with Meldrum’s acid and trimethylorthoformate in 1-butyl-3-methylimidazolium bromide at a moderate temperature to afford 5-{(substituted aryl/4-methylthiazolyl/substituted benzothiazolyl)methylene}-2,2-dimethyl-1,3-dioxane-4,6-dione. The resulting compounds upon cyclization in 1-butyl-3-methyl tetrafluoroborate/triflate at a moderate temperature gave the title compounds in excellent yields.     

Spiropyrans and spirooxazines

The Duff formylation of 5-bromo- or 5-chloro-8-hydroxyquinoline leads to the corresponding 7-formyl derivatives, condensation of which with 2-methyleneindolines or 3H-indolium halides in the presence of a base afforded new photochromic 6′-halo-substituted spiro[indoline-2,2′-2H- pyrano[3,2-h]quinolines]. Thermal and photo-induced isomerization of compounds obtained have been investigated by 1H NMR and UV spectroscopy.     

Synthesis of 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indoles] as a new class of ultrafast light-driven molecular switch

A new class of ultrafast light-driven molecular switch has been designed and synthesized. The reaction of 1-substituted 2-methylidene-3,3-dimethyl-2,3-dihydro-1H-indoles with 2-chloromethyl-4-nitrophenol afforded 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indoles], following a basic workup. The spectroscopic properties and nanosecond-resolved photoinduced dynamics of five compounds in the 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indole] family were investigated.     

Regio- and enantioselective copper-catalyzed addition of dialkylzinc reagents to cyclic 2-alkenyl aziridines

The reactions of some organocopper reagents with cyclic 2-alkenyl aziridines were examined. The stereoselectivity of the addition reaction of dialkylzinc can be strongly influenced by the use of phosphoramidites as ligands for copper. Chiral copper complexes of 2,2′-binaphthyl-based phosphoramidites were shown to be highly effective catalysts for the regio- (S_N2′) and anti-stereoselective addition of dialkylzinc reagents to these compounds according to a kinetic resolution protocol. The corresponding new cyclic allylic amine reaction products were obtained with a good enantioselectivity (83% ee).     

N-(2,2-Dichloro-2-phenylethylidene)arenesulfonamides in reactions with secondary amines

N-(2,2-Dichloro-2-phenylethylidene)arenesulfonamides were synthesized by a modified procedure, and their reactions with secondary amines were studied for the first time. Reactions of imines with dialkylamines proceed at room temperature to afford α,α-dichloromethylbenzene and N,N-dialkyl-N′-(arenesulfonyl)formamidines arising from the haloform cleavage of the initially formed unstable N-(1-dialkylamino-2,2-dichloro-2-phenylethyl)arenesulfonamides. When the reaction is carried out upon cooling to 0°C, the products of the nucleophilic addition of secondary amines to azomethines, N-(1-dialkylamino-2,2-dichloro-2-phenylethyl) are formed in yields of no higher than 5%. Nonempirical calculations of ¹³C-¹H spin-spin coupling constants and their experimental measurements for the series of the synthesized N-arenesulfonamides were performed to show that these compounds exist in solutions exclusively as E isomers. Preferable conformations of the investigated compounds and the relative energies of their E and Z isomers in the gas phase were determined by quantum-chemical calculations at the MP2/6-311G** level of theory. The NMR spectral data revealed restricted rotation of the N,N-dialkylamino group about the partially double C-NAlk₂ bond in the molecules of N-arenesulfonylformamidines.     

Bio-Potency and Molecular Docking Studies of Isolated Compounds from Grewia optiva J.R. Drumm. ex Burret

In the study, two novel compounds along with two new compounds were isolated from Grewia optiva. The novel compounds have never been reported in any plant source, whereas the new compounds are reported for the first time from the studied plant. The four compounds were characterized as: 5,5,7,7,11,13-hexamethyl-2-(5-methylhexyl)icosahydro-1H-cyclopenta[a]chrysen-9-ol (IX), docosanoic acid (X), methanetriol mano formate (XI) and 2,2’-(1,4-phenylene)bis(3-methylbutanoic acid (XII). The anticholinesterase, antidiabetic, and antioxidant potentials of these compounds were determined using standard protocols. All the isolated compounds exhibited a moderate-to-good degree of activity against acetylcholinesterases (AChE) and butyrylcholinesterase (BChE). However, compound XII was particularly effective with IC₅₀ of 55 μg/mL (against AChE) and 60 μg/mL (against BChE), and this inhibitory activity is supported by in silico docking studies. The same compound was also effective against DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid) radicals with IC₅₀ values of 60 and 62 μg/mL, respectively. The compound also significantly inhibited the activities of α-amylase and α-glucosidase in vitro. The IC₅₀ values for inhibition of the two enzymes were recorded as 90 and 92 μg/mL, respectively. The in vitro potentials of compound XII to treat Alzheimer’s disease (in terms of AchE and BChE inhibition), diabetes (in terms of α-amylase and α-glucosidase inhibition), and oxidative stress (in terms of free radical scavenging) suggest further in vivo investigations of the compound for assessing its efficacy, safety profile, and other parameters to proclaim the compound as a potential drug candidate.     

Suzuki arylation at positions 2 and 2 of 1,1-binaphthyls: stereochemical result depending on the sense of polarity of substrates

The first preparation of enantiomerically pure 1,1^′-binaphthyl-2,2^′-diboronic acid (by resolution) is reported. Optimization of the cross-coupling conditions was found to be crucial to achieve good yields in Suzuki arylation in approaches from both 2,2^′-diiodide or 2,2^′-diboronic acid (52-56%, with model p-tolyl reagents). Stereochemical results in these reactions were dramatically different: almost complete racemization starting from the 2,2^′-diiodide versus complete conservation of stereogenic information from the 2,2^′-diboronic acid. This novel synthetic approach, a stereoconservative Suzuki arylation of the diboronic acid, should be a valuable method for the synthesis of a new group of 2,2^′-diarylated (including functionalized) binaphthyl derivatives.