Reaction of Some Heterocyclic Formamidines with Trimethylsilylethynyllithium

The reaction of a 2-[(dimethylamino)methyleneamino]pteridine, two 2-[(dimethylamino)methyleneamino]pyrimidines, and a 2-[(dimethylamino)methyleneamino]pyrido[2,3-d]pyrimidine with trimethylsilylethynylithium in the presence of benzyl chloroformate leads to the corresponding 2-[bis(trimethylsilylethynyl)methylamino]-substituted heterocycles. A series of such substrates was prepared and some of the factors which permit this transformation were delineated. An X-ray crystal structure was determined of one of the products - 2-[bis(trimethylsilylethynyl)methylamino]-5,6,7,8-tetrahydro-3-(2,2-dimethylpropanoyloxymethyl)quinazolin-4-one.     

Preparation of amino group-containing polymers by plasma polymerization

Plasma polymerizations of bis(dimethylamino)methylsilane (BDMAMVS), bis(dimethylamino) methylvinylsilane (BDMAMVS), and trimethylsilyldimethylamine (TMSDMA) were investigated by elemental analysis, IR spectroscopy, and ESCA. Polymer deposition was fairly faster in the BDMAMVS and TMSDMA systems than in the BDMAMS system, indicating that vinyl and methyl substituents contribute to polymer formation, whereas hydrogen substituents disturb the polymer formation. IR and ESCA spectra for these polymers showed that some dependence of the polymers formed in the chemical composition on the nature of the monomers. A part of methylamino groups in these monomers were oxidized to give amido and amine oxide groups. BDMAMVS and TMSDMA yielded polymers with few fragmentations of methylamino groups, whereas the polymers formed from BDMAMS had no methylamino groups.     

Competitive electron impact induced methylene imine elimination from methyl- and dimethylamino N-heterocycles. 1—substituted melamines

Competitive intramolecular expulsion of methylene imine is evaluated for heterocyclic methylamino and dimethylamino substituents using selectively labelled N²,N²,N⁴-trimethylmelamine. In this compound methylene imine expulsion from the dimethylamino group is favored by more than 2:1 over loss from the methylamino group. The effects of other fragmentations and hydrogen randomisation are estimated independently using methylmelamines with each of the groups as the sole source of methylene imine loss.     

Investigation of the excited state structure of DCM via ultrafast electronic pump/vibrational probe

Time resolved visible pump, infrared probe transient absorption measurements of the solutes 4-dicyanomethylene-2-methyl-6-(p-(dimethylamino)styryl)-4H-pyran (DCM) and its isotopomer DCM-d6 are employed to probe the dynamics of charge transfer state formation in dimethyl sulfoxide (DMSO) and acetonitrile (MeCN). We observe a two stage charge transfer (CT): the first step is an instrument-response-limited charge separation to the dicyanomethylene group, and the second involves a structural evolution of the dimethylamino group. Theoretical calculations and isotopic substitution indicate that the observed vibration is due to the dimethylamino group twisting out of plane, stabilizing the charge separation.     

peri-Naphthalenediamines: XXXIV. 1,4,5,8-Tetrakis(dimethylamino)naphthalene: Alternative Approaches to Synthesis

New methods were proposed for synthesizing 1,4,5,8-tetrakis(dimethylamino)naphthalene with an overall yield of 4 to 12% to replace the known procedure ensuring an overall yield of 2%. Catalytic hydrogenation was shown to be inapplicable for preparation of polyaminonaphthalenes from nitro compounds having 3 or 4 nitro gruops in the -positions. Nucleophilic amination of 1,5-dinitronaphthalene in the system NH₂OH/NaOH/MeOH yields 1-amino-4-nitronaphthalene. The nitration of 1,5-bis(p-tolylsulfonylamino)naphthalene leads to formation of 2,6-dinitro rather than 4,8-dinitro derivative, as it was believed formerly. This was confirmed by transformation of the latter into 1,2,5,6-tetrakis(dimethylamino)naphthalene. 3-Nitro, 2,6-dinitro, 2,6-diamino, and 2,4,6,8-tetranitro derivatives of 1,5-bis(dimethylamino)naphthalene, nitro and amino derivatives of 1,4,5-tris(dimethylamino)naphthalene, and 4,5-diamino-1,8-bis(methylamino)naphthalene were synthesized. By treatment with perchloric acid 1,4,5,8-tetrakis(dimethylamino)naphthalene was oxidized to 2,3-dihydroperimidinium salt.     

Übergangsmetall-carben-komplexe: CXXXVIII. Neue übertragungsreaktionen von carbenliganden zur darstellung von gold-carben-komplexen

Chloroauric acid reacts with pentacarbonyl[(dimethylamino)ethoxycarbene]chromium(0) (I) to give trichloro[(dimethylamino)ethoxycarbene]gold(III) (IV), and with pentacarbonyl{(dimethylamino)[methoxy(phenyl)methyleneamino]carbene} complexes of molybdenum(0) (II) and tungsten(0) (III) to give chloro{(dimethylamino)[methoxy(phenyl)methyleneamino]carbene}gold(I) (VII) and trichloro{(dimethylamino)[methoxy(phenyl)methyleneamino]carbene}gold(III) (VIII). IV and VIII react with boron tribromide to give tribromo[(dimethylamino)ethoxycarbene]gold(III) (V) and tribromo{(dimethylamino)[methoxy(phenyl)methyleneamino]carbene}gold(III) (IX), which react with boron triiodide to yield the triiodogold complexes [(dimethylamino)ethoxycarbene]triiodogold(III) (VI) and {dimethylamino[methoxy(phenyl)methyleneamino]carbene} triiodogold(III) (X).     

THE AUTOXIDATION OF TETRAKIS-(DIMETHYLAMINO)-ETHYLENE

Abstract— The reaction of tetrakis-(dimethylamino)-ethylene (I) with oxygen in non-hydroxylic solvents gives tetramethylurea (II), tetramethyloxamide (III), tetramethyl-hydrazine (IV), and bis-(dimethylamino)-methane (V) in yields that are virtually independent of solvent and temperature, or whether chemiluminescence occurs. Autoxidation over water solutions, however, first gives octamethyloxamidinium peroxide (VI) which then hydrolyzes to give III and dimethylamine, and undergoes an alternative demethylation reaction to give tetramethyl 2-(dimethylamino)-2-hydroxy-2-(methylamino)-acetamidinium (VIII) and formate (IX) salts. Both courses of autoxidation are observed in solutions containing lithium chloride, in methanol or in water-dioxane mixtures. A common intermediate is suggested.     

Antiselective Three‐Component Mannich Reactions in Thiopyran‐4‐one System

The one‐pot, three‐component Mannich reactions of thiopyran‐4‐one 1 with different aromatic aldehydes and aniline derivatives in the presence of catalytic quantities of ZrOCl₂.8H₂O (15 mol %) led to rapid and high yield formation of various 3‐methylamino substituted derivatives of 1 at room temperature. Spectroscopic and X‐ray analyses of the products suggested the formation of the anti stereoisomers as the major product of the reactions.     

芳基异方酰胺与HMPA及一些羧酰胺的反应

研究了1,3-双芳基异方酰胺与六甲基磷酰三胺(HMPA)及其它羧酰胺的反应制得了15个既含芳胺基又含脂肪基的不对称方酰胺。该反应提供了制备既含芳胺基又含二甲胺基、甲胺基和乙胺基的不对称方酰胺的较为有效的方法。对反应机理作了初步讨论。     

Photoproduct formation with 4-aminobenzonitriles in acetonitrile and its effect on photophysical measurements

Upon photoexcitation of 4-(dimethylamino)benzonitrile (DMABN) in the polar solvent acetonitrile (MeCN), a methyl group is subtracted from the dimethylamino substituent, producing 4-(methylamino)benzonitrile (MABN). The fluorescence of this photoproduct MABN occurs in the same spectral range as that of the locally excited (LE) state of DMABN. As DMABN undergoes efficient fluorescence quenching in MeCN, leading to a decrease of the LE fluorescence yield by a factor of 290 at 25 degrees C, whereas MABN is not quenched at all, even small amounts of this photoproduct strongly increase the apparent contribution of the LE emission to the total dual fluorescence spectrum of DMABN. As a further consequence of the photoproduct formation, the nanosecond decay time, tau1, in the double-exponential LE fluorescence decay of DMABN in MeCN increases in relative intensity as compared to its picosecond counterpart, tau2, as the fluorescence lifetime of MABN is similar to the tau1 decay time of DMABN. The presence of the photoproduct MABN therefore can lead to a misinterpretation of the kinetic data derived from photostationary and time-resolved fluorescence experiments with DMABN in polar solvents. Photoproducts are also observed with 4-(N-pyrrolidinyl)aminobenzonitrile (P5C) and 4-(N-piperidinyl)aminobenzonitrile (P6C) in MeCN. In the case of P5C, 4-cyano-N-phenylpyrrole (PP4C) is the main product, whereas photolysis of P6C produces 4-aminobenzonitrile (ABN), among other photoproducts. This photodegradation, leading to the appearance of multiexponential decays, likewise has a negative influence on the ICT and LE fluorescence spectra and fluorescence decays of P6C and P5C, again impairing the validity of the kinetic analysis of these data. The isosbestic (absorption) and isoemission (fluorescence) points encountered in the spectra of DMABN and P6C during photoirradiation indicate that at least one photoproduct is formed.     

Proximity effects in the mass spectra of crowded bis(dimethylamino)arenes: Part II—Rearrangements of the molecular radical cations of ‘proton sponges’ by reciprocal methyl/hydrogen transfer

The EI induced fragmentation pathways of 4,5-bis(dimethylamino)fluorene, 4-(d₆-dimethylamino)-5-(dimethylamino)fluorene, 4,5-bis(d₆-dimethylamino)fluorene, 4-(dimethylamino)-5-methylaminofluorene, 4,5-bis-(methylamino)fluorene, 4-amino-5-methylaminofluorene, 1,8-bis(dimethylamino)naphthalene, 1,8-bis(d₆-dimethyl-amino)-naphthalene and 1,8-bis(dimethylamino)-2,7-dimethoxynaphthalene were investigated. A mechanism is pro-posed for the surprising elimination of CH₃? NH₂ from the molecular ion, followed by loss of C₂H₅·, C₂H₄ and CH₃CN and for the accompanying cyclizations to stable heterocyclic ions: prior to fragmentation the molecular radical ion rearranges to new, distonic radical ions by reciprocal H and CH₃ transfers between the adjacent dimethylamino groups. Each of these new, isomeric molecular ions decomposes subsequently in a characteristic way.     

2'-O-[2-(amino)-2-oxoethyl] oligonucleotides

[structure: see text] Oligonucleotides with novel modifications, 2'-O-[2-(amino)-2-oxoethyl] (2'-O-NAc), 2'-O-[2-(methylamino)-2-oxoethyl] (2'-O-NMAc), 2'-O-[2-(dimethylamino)-2-oxoethyl] (2'-O-DMAc), and 2'-O-[2-[[2-(dimethylamino)ethyl]amino]-2-oxoethyl] (2'-O-DMAEAc), have been synthesized. These modified oligonucleotides exhibit high binding affinity to complementary RNA (and not to DNA) and considerably enhance the nuclease stability of oligonucleotides with t(1/2) > 24 h.     

Lithiation of 2-Alkyl-3-amino- and 2-Alkyl-3-(methylamino)-4(3H)-quinazolinones(1)

3-Amino-2-methyl-4(3H)-quinazolinone has been doubly lithiated, on nitrogen and in the 2-methyl group, with n-butyllithium. The lithium reagent thus obtained reacts with a variety of electrophiles (D(2)O, benzophenone, cyclohexanone, cyclopentanone, acetophenone, benzaldehyde, tetraisopropylthiuram disulfide (TITD)) to give the corresponding 2-substituted derivatives in very good yields. Reactions of the dilithio reagent with 2 molar equiv of methyl iodide or phenyl isocyanate give disubstituted derivatives. Double lithiation of the 2-ethyl and 2-propyl analogues have been achieved using LDA, and subsequent reactions with most electophiles are then similar. In the reaction of the dianion of the 2-ethyl compound with TITD, deamination from position 3 takes place with the formation of the 2-substituted derivative. In reactions with prochiral ketones, the dianion of the 2-ethyl compound gives very high diastereoselectivity. Lithiation and subsequent reactions of 3-(methylamino) analogues take place in a similar manner, thus providing access to a range of substituted 3-(methylamino)-2-alkyl-4(3H)-quinazolinones by a general procedure. Lithiation of 3-(dimethylamino)-2-ethyl-4(3H)-quinazolinone did not take place under similar conditions. Lithiation of 3-amino-2-unsubstituted-4(3H)-quinazolinone was also unsuccessful.     

Cholinesterase‐Inhibiting New Steroidal Alkaloids from Sarcococca hookeriana of Nepalese Origin

Bioassay‐guided phytochemical investigation of Sarcococca hookeriana has resulted in the isolation and structure elucidation of five new pregnane‐type steroidal alkaloids: (?)‐hookerianamide A (=(2β,3β,4β,20S)‐20‐(dimethylamino)‐3‐[(3‐methylbut‐2‐enoyl)amino]‐5α‐pregn‐16‐ene‐2,4‐diol; 1 ), (+)‐hookerianamide B (=(2α,3β,4β,20S)‐4‐acetoxy‐20‐(dimethylamino)‐3‐[(3‐methylbut‐2‐enoyl)amino]‐5α‐pregnan‐2‐ol; 2 ), (?)‐hookerianamide C (=(2β,3β,20S)‐2‐acetoxy‐20‐(dimethylamino)‐3‐[(3‐methylbut‐2‐enoyl)amino]‐5α‐pregnane; 3 ), (?)‐hookerianamine A (=(3β,20S)‐20‐(dimethylamino)‐3‐(methylamino)‐5α‐pregn‐14‐ene; 4 ), and (+)‐phulchowkiamide A (=(3β,20S)‐20‐(methylamino)‐3‐[(2‐methylbut‐2‐enoyl)amino]‐5α‐pregn‐2‐en‐4‐one; 5 ). These compounds, as well as the two chemically derived acetyl derivatives 6 and 7 , displayed cholinesterase inhibition in a concentration‐dependent manner.     

An approach to estimate the energy and strength of the intramolecular hydrogen bond in different conformers of 4‐methylamino‐3‐penten‐2‐one

The molecular structure and intramolecular hydrogen bond energy of 32 conformers of 4‐methylamino‐3‐penten‐2‐one were investigated at MP2 and B3LYP levels of theory using the standard 6–31G** basis set and AIM analyses. Furthermore, calculations for all the possible conformations of 4‐methylamino‐3‐penten‐2‐one in water solution were also carried out at B3LYP/6–31G** level of theory. The calculated geometrical parameters and conformational analyses in gas phase and water solution show that the ketoamine conformers of this compound are more stable than the other conformers (i.e., enolimine and ketoimine). This stability is mainly due to the formation of a strong N? H···O intramolecular hydrogen bond, which is assisted by π‐electrons resonance. Hydrogen bond energies for all conformers of 4‐methylamino‐3‐penten‐2‐one were obtained from the related rotamers method. The nature of intramolecular hydrogen bond existing within 4‐methylamino‐3‐penten‐2‐one has been investigated by means of the Bader theory of atoms in molecules, which is based on topological properties of the electron density. The results of these calculations support the results which obtained by related rotamers method. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Darstellung und Sulfurierung von 4,5-Benzo-2-{[2-(dimethylamino)ethyl]methyl-amino}-3-methyl-1,3,2-oxazaphosphorinan-6-on; Molekülstruktur eines Tetracarbonylmolybdän(0)-Chelatkomplexes

4,5-Benzo-2-{[2-(dimethylamino)ethyl]methylamino}-3-methyl-1,3,2-oxazaphosphorinan-6-one – Preparation, Sulfuration, and Molecular Structure of a Tetracarbonyl Molybdenum Derivative The synthesis of the title compound 4 is described. It reacts with sulfur to yield the thiophosphoryl derivative 5 . The structure of the molybdenum(0) complex 6 , containing 4 as a bidentate ligand, was established by X-ray analysis and is compared to that of the related 2-{[2-(dimethylamino)ethyl]methyl-amino}-1,3,2-benzodioxaphosphole-tetracarbonylchromium(0)-complex 7 [1]. 6 , similarly to 7 , shows a nearly rectangular ?bite”? angle, with 4 functioning as a chelating ligand, coordinating to Mo(0) via P(III) and the nitrogen atom of the NMe₂ group. The heterocyclic part of the ligand displays a distorted envelope configuration.     

Nanoporous thin films from ionically connected diblock copolymers

An ionically connected polystyrene-block-poly(ethylene oxide) diblock copolymer (PS^?+PEO) has been prepared by blending a PEO block functionalized by a dimethylamino group at one extremity with a sulfonic acid terminated PS block. Proton transfer occurs from the sulfonic acid to the dimethylamino group, resulting in the formation of an ion pair acting as a junction between the two polymer blocks. This copolymer was further used to prepare thin films with a cylindrical morphology consisting of PEO cylinders embedded in a PS matrix and oriented perpendicularly to the film surface. Nanoporous thin films with sulfonate groups on the pore walls have been finally obtained after solvent extraction of the PEO microphases. The presence of those sulfonate groups was evidenced by grafting a positively charged fluorescent dye on the pore walls.     

Nucleophilic substitution in benzo-1,2,3,4-tetrazine 1,3-dioxides

Nucleophilic substitution in nitro- and bromobenzo-1,2,3,4-tetrazine 1,3-dioxides (BTDOs) was studied. In most cases, the bromo and nitro groups are replaced by methylamino, dimethylamino, azido, and methoxy groups without opening of the tetrazine ring. It was illustrated with the reactions of dibromo-BTDOs with sodium methoxide that the reactivity of positions 5 to 8 in their benzene ring as regards nucleophilic substitution changes in the following order: 6 > 8 > 7 > 5. The structures of the BTDOs obtained were confirmed by ¹H, ¹³C, and ¹⁴N NMR data.     

Dative sigma- and pi-bonding in boron-nitrogen compounds: molecular structures of (CH3)2NB(CH3)N(CH3)B(CH3)2 and [(CH3)2B]2NN(CH3)2 determined by gas electron diffraction and quantum chemical calculations

The molecular structures of dimethylamino[(dimethylboryl)methylamino]methylborane, Me2NBMeNMeBMe2 (1) and 1,1-bis(dimethylboryl)-2,2-dimethylhydrazine, (Me2B)2NNMe2 (2) have been determined by gas electron diffraction (GED), density functional theory calculations at the B3PW91/6-311++G** level and ab initio calculations at the MP2/6-311++G** level. 1 adopts an open structure similar to that of the isoelectronic hydrocarbon molecule permethylbutadiene; the central B-N bond distance at 148.0/149.3(7) pm (MP2/GED) corresponds to a single covalent N--B bond distance, the two terminal distances, 140.9/140.5(4) pm and 141.8/141.3(4) pm, correspond to the distance between N and B atoms joined by a covalent sigma-bond and a dative pi-bond. A closed form where the establishment of a dative bond between the terminal N and B atoms has led to the formation of a four-membered ring also corresponds to a minimum on the potential energy surface, but the energy is calculated to be 14.3 kJ mol(-1) higher at the MP2 level. This structure is also incompatible with the GED data. 2 adopts a structure in which a dative sigma-bond between the dimethylamino N atom and one of the boron atoms has led to the formation of a three-membered N(2)B ring. The dative sigma-bond distance is 165.5/164.0(13) pm, the two other bond distances in the ring are N-B=150.6/148.9(9) pm corresponding to a covalent sigma-bond and N-N=145.1/145.4(3) pm. The terminal B--N distance 139.6/138.9(9) pm is consistent with a covalent sigma-bond augmented by a dative pi-bond. An open Y-shaped structure also corresponds to a minimum on the potential energy surface, but the energy is 18.7 kJ mol(-1) higher (MP2) and it is incompatible with the GED data.     

Syntheses and evaluation of fluorinated benzothiazole anilines as potential tracers for β-amyloid plaques in Alzheimer's disease

[¹¹C]2-(4′-(Methylamino)phenyl)-6-hydroxybenzothiazole ([¹¹C]PIB) is a most potential PET tracer for detecting the β-amyloid plaques in Alzheimer's disease. Here the syntheses of three fluorinated PIB, namely 2-(4′-(methylamino)phenyl)-6-fluoroethoxybenzothiazole (O-FEt-PIB), 2-(4′-(methylamino)phenyl)-6-fluoro-benzothiazole (F-N-Me) and 2-(4′-(dimethylamino)phenyl)-6-fluorobenzo-thiazole (F-N,N-Me), and the radiosynthesis of one corresponding ¹⁸F-labeled PIB compound, [¹⁸F]O-FEt-PIB, as well as their in vitro/in vivo biological characters were reported. The structures of the products were confirmed by IR, ¹H NMR, EI/ESI-MS, elemental analysis and HRMS techniques. The radiolabeled product was characterized by radio-TLC and radio-HPLC and purified by semi-preparative radio-HPLC. The suitable biological characters showed these tracers were potential to be developed as probes for detecting β-amyloid plaques in Alzheimer's disease.