1-Aryltetralin privileged structure-based libraries: parallel synthesis of N-aryl and N-biaryl γ-lactam lignans

The parallel solution-phase synthesis of two libraries of product-like compounds derived from a 1-aryltetralin privileged structure is described. The N-aryl picropodophyllone γ-lactams were synthesized from methyl ester thuriferic acid via InCl₃-tandem aza-Michael addition-cyclization reaction of anilines. Bromo-aryl compounds from this library were subjected to a ligandless palladium Suzuki cross-coupling to give the expected N-biaryl picropodophyllin γ-lactams.     

Cycloisomerization of (arene)chromium complexes with enyne by gold(I) catalyst for axially chiral biaryls

Planar chiral arene chromium complexes with enyne bond gave stereoselectively axial biaryl chromium complexes by gold(I) catalyzed cycloisomerization in good yields. Arene chromium complexes with enyne bonds were treated with triphenylphosphine gold bis(trifluoromethanesulfonyl)imidate in methylene chloride to give anti-biaryl monochromium complexes without formation of stereoisomers.     

Synthesis, characterization and crystal structures of boron-containing intermediates in the reductive amination of ferrocenecarboxaldehyde to a bis(ferrocenylmethyl) amine

Reaction of ferrocenecarboxaldehyde with aqueous methylamine leads to [(methylimino)methyl]ferrocene, which is reduced to N-(ferrocenylmethyl)-N-methylamine by NaBH₄. This amine reacts with ferrocenecarboxaldehyde and NaCNBH₃ to give the tertiary ammonium salt, di(N-(ferrocenylmethyl))-N-methylammonium cyanoborohydride. Hydrolysis of the NaCNBH₃ reaction mixture produces the free amine, di(N-(ferrocenylmethyl))-N-methylamine. Thermolysis of di(N-(ferrocenylmethyl))-N-methylammonium cyanoborohydride in refluxing tetrahydrofuran converts it to the cyanoborane adduct, di(N-ferrocenylmethyl)-N-methylamine-cyanoborane, with elimination of H₂. The new compounds are fully characterized by using spectroscopic and physical methods, including X-ray crystal structure determinations of di(N-(ferrocenylmethyl))-N-methylammonium cyanoborohydride, di(N-(ferrocenylmethyl))-N-methylamine, and di(N-(ferrocenylmethyl))-N-methylamine-cyanoborane.     

Asymmetric synthesis of enantio-enriched acyclic α-amino alkylstannanes and rearrangement behavior of carbanions thereof

An efficient stereocontrolled synthesis of enantio-enriched N-Boc-N-allyl-α-amino alkylstannanes and N,N-diallylic α-amino alkylstannanes starting from enantio-enriched α-hydroxy alkylstannane has been developed. The aza-Wittig rearrangement of enantio-defined N,N-diallyl-α-amino alkyllithium, generated by tin-lithium exchange, is shown to proceed predominantly with inversion of configuration at the Li-bearing carbon terminus.     

Synthesis, properties, and molecular structure of nitro-substituted N-methyl-N-nitroanilines

Ten mono-, di-, and trinitro derivatives of N-methyl-N-nitroaniline were synthesized and studied by spectral, electrooptical, and quantum-chemical methods. Three of these derivatives, N-methyl-N,2,3-trinitroaniline, N-methyl-N,2,5-trinitroaniline, N-methyl-N,3,5-trinitroaniline, were also examined by the X-ray diffraction method. The N-nitroamino group in their molecules is almost planar, the N⁷-N⁸ bond is shortened, and the N⁸ atom is characterized by a strong deficit of electron density. The dihedral angle between the planes of the N-nitroamino group and the benzene ring is 56°–92°, which makes conjugation between these fragments impossible. The N-nitroamino group in the examined compounds acts as a weak electron donor with respect to the nitro groups in the aromatic ring; the mechanism of this effect is inductive.     

Use of a flow-injection system in the evaluation of the characteristic behavior of neutral carriers in lithium ion-selective electrodes

A flow-injection system based on microconduits is used to investigate electrode characteristics such as selectivity, detection limit, and response and equilibrium times of the new ionophore, N,N,N′,N′-tetraisobutyl-5,5-dimethyl-3,7-dioxanonane diamide, in lithium ion-selective electrodes. These characteristics were compared with those of the ionophore N,N′-diheptyl-N,N′,5,5-tetramethyl-3,7-dioxanone diamide. The new ionophore has superior detection limits and shorter response and equilibrium time, but the other exhibits better selectivity for lithium with respect to sodium. Values of K^Pot_LiNa for the new ionophore vary from 0.0450 to 0.566, depending on the methods of measurement and solution conditions. This phenomenon is discussed. Stop-flow experiments effectively demonstrated the response and equilibrium time differences between these two ionophore membranes.     

Reactivity of the radical cation of 4-(N,N-dialkylamino)biphenyl derivatives as probed by resonance Raman spectroscopy

The cw resonance Raman spectra of the products of electrochemical oxidation of 4-(N,N-dialkylamino)biphenyl compounds, with alkyl = methyl, methyl-d₃ or ethyl, are analyzed and compared with the time-resolved resonance Raman spectra of the photogenerated radical cation of these amines. The anodic oxidation is shown to lead to the formation of the respective N,N,N′,N′-tetraalkylbenzidine radical cation and dication, and a mechanism scheme for the oxidation is proposed.     

Über die Si3-N-bindung: XXXV. Darstellung von N-β-halogenäthyl-N,N-bis(trimethylsilyl)aminen

N-β-Haloethyl-N,N-bis(trimethylsilyl)amines, which can be used for the introduction of aminoethyl groups into organic or organosilicon compounds, are prepared in good yields from N-trimethylsilylaziridine and trimethylhalosilanes. This reaction is spontaneous with trimethylbromo- and -iodosilane, whereas it is necessary to run the reactions with trimethylchlorosilane in the presence of dipolar aprotic solvents and at higher temperatures.N-β-Bromoethyl-N,N-bis(trimethylsilyl)amine (II) is also obtained by silylation of N-β-bromoethylamine hydrobromide with trimethylsilyldiethylamine or with N-trimethylsilyl-N-methyl acetamide. Furthermore N-β-iodoethyl-N,N- bis(trimethylsilyl)amine is prepared by the reaction of II with MgI₂ or of aziridine and N-trimethylsilylaziridine respectively, with trimethylchlorosilane and MgI₂.From the silylation of N-β-bromoethylamine hydrobromide with trimethylsilyldiethylamine N,N-bis(trimethylsilyl)-N′,N′-diethylethylenediamine is isolated as a side product or, at higher temperatures, as the main product.     

Deoxygenation of tertiary amine N-oxides under metal free condition using phenylboronic acid

A simple and efficient method for the deoxygenation of amine N-oxides to corresponding amines is reported using the green and economical reagent phenylboronic acid. Deoxygenation of N,N-dialkylaniline N-oxides, trialkylamine N-oxides and pyridine N-oxides were achieved in good to excellent yields. The reduction susceptible functional groups such as ketone, amide, ester and nitro groups are well tolerated with phenylboronic acid during the deoxygenation process even at high temperature. In addition, an indirect method for identification and quantification of tert-amine N-oxide is demonstrated using UV–Vis spectrometry which may be useful for drug metabolism studies.     

Effect of solvent nature on free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride and maleic acid

The free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid in DMSO proceeds to yield statistical copolymers. When the reaction is carried out in methanol, the copolymers of constant compositions (N,N-diallyl-N,N-dimethylammonium chloride: maleic acid = 2: 1) are formed over a wide range of comonomer ratios in the starting mixture. The formation of alternating copolymers in this case may be attributed to formation of donor-acceptor complexes between the comonomers in the methanol solution, as evidenced by UV spectrophotometry. The kinetic features of the process have been investigated, and the relative activities of the monomers have been assessed. ¹³C NMR studies have demonstrated that, regardless of the solvent nature, both double bonds of N,N-diallyl-N,N-dimethylammonium chloride are involved in copolymerization via intermolecular cyclization accompanied by formation of pyrrolidinium structures.     

Use of Stille-type cross-coupling as a route to oligopyridylimines

The new tin reagents, 2-(n-Bu₃Sn)-6-{C(R)OCH₂CH₂O}-C₅H₃N, (R=H a, Me b), have been employed in Stille-type cross-coupling reactions with a range of oligopyridylbromides generating, following a facile deprotection step, a series of formyl- and acetyl-functionalised oligopyridines. Condensation reactions with 2,6-diisopropylaniline has allowed access to families of novel sterically bulky multidentate N,N,N,N (tetradentate), N,N,N,N,N (pentadentate), N,N,N,N,N,N (sexidentate) and N,N,N,N,N,N,N (heptadentate) nitrogen donor ligands. This work represents a straightforward and rapid synthetic route for the preparation of oligopyridylimines, which are expected to act as useful components for the self-assembly of polymetallic complexes.     

Effect of the solvent on the properties of solutions of polysulfone-polyethersulfone blends

The effect of the solvent on the properties of concentrated solutions of polysulfone-polyethersulfone blends, which can be used to produce film and fibrous materials, is studied. It is found that equiconcentrated solutions of polysulfone-polyethersulfone blends, at the same ratio of polymers in N,N-dimethylacetamide and N-methyl-2-pyrrolidone, significantly differ in structure and rheological and optical properties. Solutions in N,N-dimethylacetamide are polydisperse emulsions, while solutions in N-methyl-2-pyrrolidone are systems composed of closely sized interpenetrating fields of polysulfone and polyethersulfone solutions, in which the dispersed phase and the dispersion medium cannot be detected. The turbidity-spectrum method is used to show that, after the introduction of the second (incompatible) polymer, the average size of supramolecular particles significantly increases in N,N-dimethylacetamide and hardly changes in N-methyl-2-pyrrolidone relative to the particle sizes in solutions of the individual polymers. It is determined that these differences results from the different thermodynamic qualities of N,N-dimethylacetamide and N-methyl-2-pyrrolidone with respect to polysulfone.     

Homolytic displacement at carbon centres: XII. Regiospecific formation of N-allyl and N-cyclopropylcarbinyl sulphonamides and of allyl and cyclopropyl halides in the reaction of N-halogeno compounds with organocobaloximes

Several but-3-enyl and allylcobaloximes react regiospecifically with N-chloro-N-methyl sulphonamides to give N-cyclopopylcarbinyl- or rearranged N-allyl-N-methyl sulphonamides, by a process which is believed to take place by the attack of an N-centred radical at the terminal unsaturated carbon of the organic ligand, with displacement of cobaloxime(II). In contrast, N-bromoacetamide and several other N-halogenoimides react regiospecifically to give the cyclopropylcarbinyl halide or the rearranged allyl halide by a process in which a halogen-containing free radical species attacks the terminal unsaturated carbon of the organocobaloxime.     

P′CP′-Pincer palladium complex-catalyzed allylation of N,N-dimethylsulfamoyl-protected aldimines

The P′CP′-pincer palladium complex-catalyzed allylation of N,N-dimethylsulfamoyl-protected aldimines with allyl(tributyl)stannane is investigated for the preparation of N-homoallylic sulfamides. The desired N,N-dimethylsulfamoyl-protected products are obtained in moderate to high yields in DMF under very mild conditions and a high yielding and convenient deprotection of the N,N-dimethylsulfamoyl group is also demonstrated.     

NMR chemical shifts and coupling constants of various nuclei of N,N-diethylbenzenesulfenamide,N,N-diethylbenzeneseleneamide and some related sulfur amides

The ⁷⁷Se, ¹⁵N, ¹³C and ¹H NMR parameters have been determined for N,N-diethylbenzenesulfen- and N,N-diethylbenzeneseleneamide and the ¹H¹³C coupling constants additionally for N,N-dimethylmethanesulfinamide, N,N-dimethylbenzenesulfinamide, N,N-dimethylmethanesulfonamide, N,N-dimethylbenzenesulfonamide and diphenylsulfone. The nitrogen-15 nucleus is slightly more shielded in the sulfenamide than in the seleneamide. Compared to sulfin- and sulfonamides the nitrogen nuclei of these amides are more shielded. The solvent effects on the chemical shift of both selenium-77 and nitrogen-15 nuclei are observable. The nitrogen-15 chemical shifts of sulfur and seleneamides are less sensitive to the solvents than those of carboxamides. This change in the nitrogen-15 chemical shift in sulfen- and seleneamide is the same order of magnitude, but opposite in direction compared with that in sulfon- and sulfinamides. The ¹H¹³C direct aromatic coupling constants increase along with the increasing oxidation state of sulfur in sulfur amides, being greatest in sulfonamides.     

Fluorsilylsubstituierte N,N- und N,O-bis(trimethylsilyl)-hydroxylamine

Fluoro- und aminofluoro-silanes react with the lithium salt of N,O-bis(trimethylsilyl)hydroxylamine under LiF elimination and substitution. Alkyl- and amino-fluorosilanes give O-fluorosilyl-N,N-bis(trimethylsilyl)hydroxylamines, arylfluorosilanes give N-fluorosilyl-N,O-bis(trimethylsilyl)hydroxylamines. By the further reaction of O-difluorosilyl-N,N-bis(trimethylsilyl)hydroxylamine with the lithiated hydroxylamine, O,O′-fluoromethylsilyldi[N,N-bis(trimethylsilyl)hydroxylamine] is formed. On heating N-difluorophenylsilyl-N,O-bis(trimethylsilyl)hydroxylamine di[fluorophenylsilyl(methyl)amino]pentamethylsiloxane is formed by methyl group migration. The NMR and mass spectra of the compounds are reported.     

Reactions of N-substituted 2,6(3,5)-dialkyl-1,4-benzoquinone imines with arenesulfinic acids

The regioselectivity in the reactions of N-arylsulfonyl-2,6-dialkyl-1,4-benzoquinone imines with arenesulfinic acids (1,6-, 6,1-, or 6,3-addition) is determined by steric factor, while in the reactions of N-aroyl-1,4-benzoquinone imines electronic effect of substituents in the quinoid ring is crucial. The reactions of N-arylsulfonyl-3,5-dimethyl-1,4-benzoquinone imines with arenesulfinic acids follow mainly the 1,4-addition pattern. N-(N-Arylsulfonylbenzimidoyl)-1,4-benzoquinone imines are capable of reacting in a way similar to both N-arylsulfonyl and N-aroyl derivatives.     

Easily assembled,modular N,O-chelating ligands for Ta(V) complexation: a comparative study of ligand effects in hydroaminoalkylation with N-methylaniline and 4-methoxy-N-methylaniline

The influence of structurally related N,O-chelating ligands with additional heteroatoms (N, O, P, S) on the reactivity of in situ generated tantalum complexes for the hydroaminoalkylation of amines has been explored. Reactivity was probed by evaluating the catalytic ability of these N,O-chelating systems with N-methylaniline and 4-methoxy-N-methylaniline substrates. Enhanced reactivity is observed with amide proligands bearing an ortho-methoxyphenyl group on the nitrogen. 4-Methoxy-N-methylaniline is found to be more prone to undergo C–H functionalization via hydroaminoalkylation than N-methylaniline. The use of the related substrate 2-methoxy-N-methylaniline is not tolerated, and instead C(sp³)–O bond cleavage was observed.     

Pyridinium N-heteroarylaminides: synthesis of N-heteroaryltetramines based on 1,6-bis(phenoxy)hexane and 1,3-bis(phenoxymethyl)benzene

The synthesis of a set of new N-heteroaryltetramines is reported. A regioselective alkylation on the N-exo nitrogen of pyridinium N-(heteroaryl)aminide with the corresponding tetrabromo compounds, followed by a clean N-N bond reduction of the corresponding tetra-salts, allowed an easy and general method to obtain N,N′,N″,N?-tetrakis(2-heteroaryl)tetramines.     

New access to azido-substituted alkylnitramines

A new versatile access to azido-substituted N-alkylnitramines is based on ring opening in N-nitrooxazolidines and N-nitroperhydro-1,3-oxazines with thionyl chloride followed by treatment with sodium azide. Representative N,N-bis(azidoalkyl)- and N-azidoalkyl-N-methoxymethyl- containing nitramines were synthesized and characterized.