From N,N-diphenyl-N-naphtho[2,1-b]thieno[2,3-b:3′,2′-d]dithiophene-5-yl-amine to propeller-shaped N,N,N-tri(naphtho[2,1-b]thieno[2,3-b:3′,2′-d]dithiophene-5-yl)-amine: syntheses and structures

Three unique propeller-shaped helicenyl amines compounds: N,N-diphenyl-N-naphtho[2,1-b]thieno[2,3-b:3′,2′-d]dithiophene-5-yl-amine (1), N-phenyl-N,N-di(naphtho[2,1-b]thieno[2,3-b:3′,2′-d]dithiophene-5-yl)amine (2), and N,N,N-tri(naphtho[2,1-b]thieno[2,3-b:3′,2′-d]dithiophene-5-yl)amine (3) were efficiently synthesized by Wittig reaction and oxidative photocyclization. The crystal structures of 1, 2 and molecular configuration optimization (DFT-B3LYP/6-31+G(d)) of 3 reveal that the steric hindrance from the moiety of trithia[5]helicene effectively forces the nitrogen atom and the three bonded carbon atoms to coplanar and the interplanar angles of the facing terminal thiophene ring and benzene ring becoming larger when the helical arm increased from 1 to 3. Electrochemical properties and UV–vis absorption behaviors of 1, 2, 3 were primarily determined by the moiety of trithia[5]helicene.     

Synthesis and characterization of polar functional group substituted mono- and bis-(o-carboranyl)-1,3,5-triazine derivatives

Synthesis, structural characterization, and biological activity studies of o-carborane-substituted 1,3,5-triazines (9-12) containing polar functional groups such as methoxyethyl and t-butoxycarbonylmethyl amine units are described. De-methylation of di(methoxyethyl)amine functionalized triazines 9 and 10 resulted in the production of di(hydroxyethyl)amine derivatives 13 and 14. NMR (¹H and ¹³C) and X-ray crystallographic studies confirmed the structures derived from the sequential o-carborane substitution on the 1,3,5-triazine core. Preliminary in vitro studies revealed that compounds 9, 10, 13, and 14, despite their low cytotoxicity, accumulated at high levels in B-16 melanoma cells.     

Simultaneous stereoselective 4-amination with cyclic secondary amines and 2-O-deacetylation of peracetylated sialic acid derivatives

Treatment of methyl 5-acetamido-2,4,7,8,9-penta-O-acetyl-3,5-dideoxy-β-l-glycero-d-galacto-2-nonulopyranosidonate (1) with cyclic secondary amines in pyridine at room temperature for 24 h afforded unusual products (2a-g). Related experiments were carried out to explain the formation of 4-amination and 2-O-deacetylation of peracetylated sialic acid derivatives (2a-g). This reaction may provide a new strategy for the preparation of Zanamivir analogues as neuraminidase inhibitors for anti-H5N1 subtype of avian influenza virus (AIV).     

Polyaromatic amines. Part 3: Synthesis of poly(diarylamino)styrenes and related compounds

The title compounds were synthesised and characterised as part of a study into new aromatic amines for charge transporting materials. Compounds 12-16, 20-24 and 27-34 are alkene linked triarylamines, compounds 35-36 are hydrazone derivatives and compounds 38-41 are pyrrole substituted triarylamines. Each compound was characterised by cyclic voltammetry.     

Reactions of 4-substituted 5H-1,2,3-dithiazoles with primary and secondary amines: fast and convenient synthesis of 1,2,5-thiadiazoles, 2-iminothioacetamides and 2-oxoacetamides

The treatment of 5H-1,2,3-dithiazole-5-thiones 1 in chloroform under reflux and 5H-1,2,3-dithiazol-5-ones 2 in THF at room temperature with primary aliphatic amines and benzylamine afforded 1,2,5-thiadiazole-3(2H)-thiones 3 and 1,2,5-thiadiazol-3(2H)-ones 6, respectively. The structure of dithiazolone 3f was confirmed by X-ray diffraction analysis. The reaction of dithiazolone 2e bearing an electron-donating methyl group in the 4-position gave 2-oxoacetamide 7e in high yield. The reaction of thiones 1 with secondary aliphatic amines in DMSO yielded 2-iminothioacetamides 8 in moderate yields together with elemental sulfur. Interestingly, the treatment of dithiazolones 2 with secondary amines under the same conditions afforded 2-oxoacetamides 9—the products of the hydrolysis of corresponding imino derivatives 10, which was isolated as 10b. A general mechanism was proposed for the formation of the products.     

Amphiphilic perfluoroalkylated sulfones and sulfonate betaines

Two types of perfluoro alkyl-containing amphiphilic sulfones 7-9 and 13-15, respectively, and sulfonate betaines 23-32 were prepared using 2-[(perfluoroalkyl)methyl]oxiranes (1-3, R_F = C₄F₉, C₆F₁₃, C₈F₁₇) or 3-(perfluoroalkyl)propyl iodides (16 and 17, R_F = C₆F₁₃, C₈F₁₇) as the starting compounds. The overall yields of two-step syntheses were above 90%. The compounds 7-9 were prepared by the reaction of oxiranes 1-3 with 2-sulfanylethan-l-ol and subsequent oxidation of intermediate sulfides. Similarly, the amphiphiles 13-15 were obtained by analogous reaction of oxiranes 1-3 with thiomorpholine and subsequent oxidation of the sulfur atom in the morpholine ring. In the syntheses of betaines 23-32, the starting compounds 1-3 or 16 and 17 were first reacted with dimethylamine followed by the ring-opening reaction of the intermediate fluoroalkyl(dimethyl)amines with propane-1,3- or butane-1,4-sultones.     

Studies on the solvent dependence of the carbamic acid formation from ω-(1-naphthyl)alkylamines and carbon dioxide

Carbamic acid formation from amine and carbon dioxide in a variety of solvents was investigated by measuring NMR (¹H, ¹³C, HMBC) and IR spectra in situ. Bubbling of CO₂ through solutions of naphthylalkylamines 1-3 in DMSO, DMF or pyridine (protophilic, highly dipolar, aprotic solvent) resulted in complete conversion of the amines to the corresponding carbamic acids 4-6. In dioxane (protophilic, dipolar, aprotic solvent), the carbamic acid and a small amount of the ammonium carbamate were formed. By contrast, in MeCN (protophobic, dipolar, aprotic solvent), in benzene or CHCl₃ (apolar, aprotic solvent), or in 2-PrOH or MeOH (dipolar, amphiprotic solvent), ammonium carbamates 7-9 rather than 4-6 were formed, although the ammonium bicarbonates/carbonates were competitively formed in MeOH. The ammonium carbamates precipitated in many cases and hence they could be separated. The selective generation of the undissociated carbamic acids in preference to the ammonium carbamates in protophilic, dipolar, aprotic solvents (DMSO, DMF, pyridine, and dioxane) is rationalized by considering the acid-base equilibria between the amines 1-3 and the carbamic acids 4-6 in nonaqueous media. The obtained selectivity is likely due to the larger pK_a values for 4-6 than the amines 1-3 in these solvents. Interestingly, the fluorescence intensities for 1-3 were dramatically enhanced (4-50 times) in DMSO or DMF upon introduction of CO₂, while they were not altered very much in dioxane, MeCN, benzene, CHCl₃, 2-PrOH, and MeOH, except small to medium increases (1.3-3 times) for 1 in dioxane, MeCN, 2-PrOH and MeOH. As a whole, the solvent effects observed in these fluorescence studies are consistent with those observed in the above NMR and IR studies. Finally, methoxycarbonylation of amine 3 into the methyl carbamate was successfully accomplished by using (trimethylsilyl)diazomethane in the presence of CO₂.     

Synthesis of fluorine containing glycolurils and oxazolines from oxides of internal perfluoroolefins

The reaction of oxides of internal perfluoroolefins 1-3 with urea gave two kinds of novel fluorine containing N-heterocyclic compounds depending on the solvent nature: 1,5-bis(perfluoroalkyl)tetraazabicyclo[3.3.0]octane-3,7-diones 4a-c and 2-amino-5-fluoro-4,5-bis(perfluoroalkyl)-4,5-dihydrooxazol-4-ols 7a-d. Use of polar dimethylsulfoxide, N,N-dimethylacetamide and acetonitrile afforded glycolurils 4a-c in moderate yields. In dioxane, unexpected cyclization occurred resulting in oxazolines 7a-d in high yields. A similar reaction of oxiranes 2, 3 with urea in aqueous dioxane gave mixtures of 4,5-dihydroxy-4,5-bis(perfluoroalkyl)imidazolidine-2-ones 9b, c, glycolurils 4b, c and oxazolines 7b-d. The molecular structure of trans-isomers of oxazoline 7b and imidazolidine 9b has been established by X-ray crystallography.     

Solid-phase synthesis of aryl, heteroaryl, and sterically hindered alkyl amines using the Curtius rearrangement

An efficient method for the solid-phase synthesis of aryl amines, heteroaryl amines, and sterically hindered alkyl amines has been developed. The key step in this process was the formation of resin-bound carbamates (B) by the Curtius rearrangement of aryl carboxylic acids with Wang resin providing the trapping hydroxyl group. N-Alkylation reactions of B gave secondary amines in good yield. Some biaryl amines, which are found widely in biologically active substances, were also prepared by the Suzuki reaction of resin-bound carbamates of 2-iodoaniline (16) or 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline (21). The developed methods can be applied to the preparation of libraries containing aryl, heteroaryl, and sterically hindered alkyl amine structures as the pharmacophores.     

Microwave-assisted synthesis of pyrazolo[3,4-d]pyrimidines from 2-amino-4,6-dichloropyrimidine-5-carbaldehyde under solvent-free conditions

The microwave-induced synthesis of pyrazolo[3,4-d]pyrimidines 4 in the reaction of N⁴-substituted-2,4-diamino-6-chloro-5-carbaldehydes 3 with hydrazine is described here. Precursors 3 have been prepared by the mono-amination of 2-amino-4,6-dichloropyrimidine-5-carbaldehyde 2 with aliphatic and aromatic amines. The reaction times with primary amines were relatively shorter than for secondary amines.     

Acyclic tertiary diamines and 1,4,7,10-tetraazacyclododecane with fluorine-containing β-diketones: Leading to low melting ionic adducts

N,N,N′,N′-Tetramethylmethanediamine (1a), N,N,N′,N′-tetramethylethanediamine (1b), N,N,N′,N′-tetramethyl-1,3-propanediamine (1c), and N,N,N′,N′-tetramethyl-1,6-hexanediamine (1d) were reacted at 25 °C with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (2a), 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (2b), 2-thenoyltrifluoroacetone (2c), and 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (2d) to form the ionic adducts 3-18. 1,4,7,10-Tetraazacyclododecane (1e) reacted at 25 °C with β-diketones (2a-d) and 1,1,1-trifluoro-2,4-pentanedione (2e) to give ionic solids 19-23 in good yields. Some of the products are liquid at 25 °C and are thermally stable over long liquid ranges as determined by thermal gravimetric analyses. Single-crystal X-ray structure determinations show that compounds 9 and 21 crystallize in the monoclinic space groups P2(1)/c and P2(1)/n, respectively. All the new compounds were characterized by ¹H, ¹⁹F and ¹³C NMR, electrospray MS and/or elemental analyses.     

Some novel observations on the reaction of 2-hydrazino-3-methylquinoxaline with trifluoromethyl-β-diketones

The reaction of 2-hydrazino-3-methylquinoxaline 1 with trifluoromethyl-β-diketones 2 not only yields the expected 5-trifluoromethyl-5-hydroxy-Δ²-pyrazolines 3a-3f and/or 3-trifluoromethylpyrazoles 4c-4f but also the unexpected products 1,2,4-triazolo[4,3-a]quinoxalines 5a-5f and/or 3(5)-trifluoromethyl-1H-pyrazoles 6c-6f. Furthermore, the acid-catalyzed dehydration of 5-hydroxypyrazolines 3a-3b resulted in the formation of unexpected 5a-5b along with the expected corresponding pyrazoles 7a-7b. These unprecedented observations provide evidence for the existence of equilibrium between the hydroxypyrazoline 3 and its open chain tautomer, ketoimine 9 in the mechanistic path leading to the formation of pyrazoles 7 and triazoles 5.     

Synthesis and characterization of the aqueous solution chemistry of the food-derived carcinogen model N-acetoxy-N-(1-methyl-5H-pyrido[4,5-b]indol-3-yl)acetamide and its N-pivaloyloxy analogue

We report the synthesis of N-acetoxy-N-(1-methyl-5H-pyrido[4,5-b]indol-3-yl)acetamide, 7, its N-pivaloyloxy analogue, 9, and improved synthesis of indole-2-acetonitrile, 3 (70% in five steps from indole-2-carboxylic acid), the carcinogenic amine Trp-P-2, 4 (40% from 3), and the nitro compound, 5 (40% from 4 by oxidation with H₂O₂ using Mo(CO)₆ catalyst). In aqueous solution at neutral pH, 7 primarily undergoes C-O bond cleavage to yield the hydroxamic acid, 8, but under the same conditions the sterically hindered 9 decomposes predominately by N-O bond cleavage with a pH independent rate constant that is 7.5-fold smaller than that for 7. In the pH range 0.5-7.0 three different processes for the decomposition of 9 were detected by kinetics. Only the process that dominates at neutral pH generates a nitrenium species that can be trapped by N₃⁻.     

A new series of heteroaromatic receptors containing the 1,3-bis(6-oxopyridazin-1-yl)propane unit: their selective transport ability towards NH4 in relation to Na, K and Ca

The synthesis of a new series of heteroaromatic macrocycles 6-9 containing the 1,3-bis(6-oxopyridazin-1-yl)propane and pyridine units is reported. The acyclic compounds 11-15 had to be prepared as the intermediates in the synthetic sequence. Evaluation of the ionophoric properties of 6-9 and 11-15 shows that 8 and 13 behave as good ammonium ion carriers and exhibit a high selectivity for ammonium with respect to spherically symmetric metallic ions like Na⁺, K⁺, and Ca²⁺. Molecular modelling of the ammonium complexes suggests that the host's oxyimino groups play a more relevant part in effective complexation than the pyridine unit, and that the high complexating efficiency of 13 might be related to the formation of a pseudocavity by intramolecular hydrogen bonding.     

Novel photo-induced oxidative cyclization of 1,3-dimethyl-5-(1-arylmethylidene)pyrimidine-2,4,6(1,3,5H)-triones: synthesis and properties of areno[5,6]pyrano[2,3-d]pyrimidine-2,4(1,3H)-dionylium ions and their photo-induced autorecycling oxidizing reaction toward some amines

Novel photo-induced oxidative cyclization was accomplished to synthesize areno[b]pyrimido[5,4-e]pyran-2,4(1,3H)-dionylium ions 13a-c⁺·ClO₄⁻. Furthermore, 13a-c⁺·BF₄⁻ and their phenyl-substituted derivatives 19a,b⁺·BF₄⁻ were alternatively synthesized by the reaction of salicylaldehyde and its naphthyl derivatives with barbituric acids and subsequent treatment with aq. HBF₄. Structural characteristics of 13a-c⁺ and 19a,b⁺ were clarified on inspection of the UV-vis and NMR spectral data as well as X-ray crystal analyses. The electrochemical properties were studied by the CV measurement. In a search for reactivity, reactions of 13a-c⁺·BF₄⁻ with some nucleophiles, hydride, benzylamine, and H₂O, were also carried out. The photo-induced autorecycling oxidation reactions of 13a-c⁺·BF₄⁻ toward some amines under aerobic conditions were carried out to give the corresponding imines (isolated by converting to the corresponding 2,4-dinitrophenylhydrazones) in 643-3600% yield (recycling number of 13a-c⁺·BF₄⁻: 6.4-36.0).     

Synthesis and characterization of boronates derived from non-symmetric amino-bis-phenols

The condensation of 2-[[(2-hydroxyphenyl)amino]methyl]-phenols (1a-1e) with different arylboronic acids led to 12 new monomeric boronates of the type 2-aryl-dibenzo[d,h]-6-aza-1,3-dioxa-2-boracyclononene (2a-2l). The boronates were characterized by ¹H-, ¹³C-, ¹¹B- and 2D-NMR experiments, FT infrared, mass spectra and elemental analyses. The stereochemistry of the H-N → B-Ph fusion is always cis, as established through the NMR spectra, as well as the X-ray structures of four boronates (2a, 2e, 2f and 2l). Hydrogen bonds between the amine proton and the oxygen ester of the five- membered ring are present in three X-ray structures (2a, 2e and 2f), while the supramolecular structure in the derivative possessing a primary amine (2l) is built up through the protons present in this moiety instead of the proton from the H-N → B-Ph fragment.     

Synthesis of new 1-substituted 4-perfluoroalkyl tetrazol-5-ones

1,3-Dipolar cycloaddition of perfluoroalkyl ethyle azides 1 with isocyanates 2 afforded 1-perfluoroalkyl-4-(n-Bu, phenyl or mesitylsulfonyl) tetrazol-5-ones 3 in good yields. The use of perfluoroalkyl ethyl azides extends the reaction to the less reactive n-butyl isocyanate.     

An efficient route for the synthesis of 2-arylthiazino[5,6-b]indole derivatives

Substituted 2-thiobenzamidomethylindole derivatives (14a-e) were prepared by the reaction of 2-aminomethylindole (9) with substituted benzoyl chlorides, followed by sulfurization using Lawesson's reagent. Alternatively, these thioamides were obtained from the amine in one step in an efficient manner by using substituted benzaldehydes in the presence of sulfur, or at room temperature with the aid of substituted methyl dithiobenzoates. The Hugerschoff reactions of thiobenzamides (14a-e) with phenyltrimethylammonium tribromide provided the rare title 2-arylthiazino[5,6-b]indoles (15a-e) in good yields. A convenient one-pot approach for the synthesis of 2-phenyl-1,3-thiazino[5,6-b]indole (15a) from 2-aminomethylindole (9) is also described.     

Perfluoroalkylated diblock-alkyl methacrylate monomers for biomedical applications: Wettability of their copolymers with HEMA and DEGMA

The intermediate perfluoroalkylated diblock hydrophobic-hydrophilic secondary alcohols (9-11), which were prepared by the reaction of monomethyl ethers of oligomeric ethyleneglycols with 2-[(perfluoroalkyl)methyl]oxiranes (7 and 8), resulted in the formation of the title monomers (12-14) by the acylation with methacryloyl chloride. Copolymers of 12-14 with HEMA and DEGMA prepared under radical conditions display enhanced swelling properties.     

Selenium dioxide-mediated synthesis of α-ketoamides from arylglyoxals and secondary amines

A facile and expeditious synthetic approach for the synthesis of α-ketoamides 3 is described. A series of α-ketoamides 3 was synthesized via reaction of selenium dioxide-mediated oxidative amidation between arylglyoxals 1 and secondary amines 2, and accelerated with microwave irradiation. Our findings indicate that constrained amines, such as piperazine and piperidine exhibit higher conversions for this transformation. This reaction was explored by synthesizing a series of α-ketoamides 3 from various arylglyoxals 1 with cyclic and acyclic secondary amines 2.