- Fractionation Factors for the Aqueous Hydroxide Ion and Solvent Isotope Effects on the Ionisation of 1,8-Bis(dimethylamino)naphthalene (Proton Sponge)
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Isotopic fractionation factors φa and φb for the hydroxy hydrogen and hydrogen bonded water hydrogens of the solvated hydroxide ion are important in controlling solvent isotop effects upon reactions involving the hydroxide ion, and were required for a vibrational analysis of the solvated ion.The product φaφb3=0.434 is accurately available from e.m.f. measurements corrected for free energies of ion transfer between H2O and D2O, but separation of φa and φb, which requires measurements in H2O-D2O mixtures is known to be subject to considerable uncertainty.Thus careful measurements with 1,8-bis(dimethylamino)naphthalene gave KD2O/KH2O=0.420 (+/-) 0.006 for the ratio of basic ionisation constants in H2O and D2O and φp=0.901 (+/-) 0.014 for the fractionation factor of the protonated base, but measurements in 1:1 H2O-D2O gave an ionisation constant too small to be consistent with any reasonable fractionation factor model for the hydroxide ion.Alternative methods of dissecting φa and φb, from measurements of isotope separation factors between hydroxide solution water vapour and autoprotolysis constants of H2O-D2O mixtures, are critically reviewed and optimum values are assessed.The results are shown to be sensitive to experimental error and to medium effects but not to departures from the Rule of the Geometric Mean.
- Chiang, Yvonne,Kresge, A. Jerry,O'Ferrall, Rory A. More
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- Decaborane anion tautomerism: Ion pairing and proton transfer control
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The reaction of 1,8-bis(dimethylamino)naphthalene - which is often referred by the trade name Proton-Sponge (PS) - with decaborane in hexane afforded [HPS][B10H13] (1) salt as a pale-yellow precipitate. Variable-temperature NMR studies allowed the full assignment of 1H and 11B spectra for this familiar ten-vertex polyhedral anion. In addition, this work reveals that an increase in the temperature leads to the intramolecular exchange of three B-H-B hydrogen atoms around the hexagonal face of the boat-shaped cluster. This previously unrecognised H-tautomerism complements the long-known low-energy proton exchange of only one of the bridging hydrogen atoms. The temperature dependent proton fluxional behaviour controls the molecular environment of the polyhedral cage, averaging the negative charge of the anion. The result is a debilitation of the cation-anion interactions in solution, favouring the transfer of the proton from the organic aromatic cation, [HPS]+, to the polyhedral anion, [B10H13]-. This proton transfer affords Proton-Sponge and decaborane, increasing the entropy of the system and sustaining an equilibrium which at high temperatures shifts toward the neutral reactants and at low temperatures moves toward the ionic products. A single X-ray diffraction analysis of 1 is discussed.
- Pérez, Sandra,Sanz Miguel, Pablo J.,Macías, Ramón
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- Base-promoted transformation of 2-C(O)R-1,8-bis(dimethylamino)naphthalenes into benzo[g]indole derivatives
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1,8-Bis(dimethylamino)naphthalenes bearing 2-positioned trifluoroacetyl or ethoxycarbonyl group on treatment with 2-lithio-1,8-bis-dimethylamino)naphthalene undergo base-promoted transformation into benzo[g]indole derivatives in small to moderate yield, representing previously unknown mode of the pyrrole ring closure which proceeds via deprotonation of the NMe group.
- Kachalkina, Svetlana G.,Borodkin, Gennady S.,Pozharskii, Alexander F.,Antonov, Alexander S.,Borodkina, Inna G.,Maltsev, Yuri F.,Filatova, Ekaterina A.,Filarowski, Aleksander,Ozeryanskii, Valery A.
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- Acid-Base Properties of Highly Substituted Diaminonaphtalenes
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The kinetic and equilibrium acid-base behaviour of four new highly hindered diaminonaphtalenes has been studied in aqueous solution or in Me2SO-H2O mixtures containing hydroxide ion.In concentrated aqueous sodium hydroxide solutions, 1,8-bis(dimethylamino)-2,7-diethoxynaphtalene and 1,8-bis(diethylamino)-2,7-diethoxynaphtalene are almost fully protonated and aqueous pKa values of 16.1 and 15.9, respectively, have been measured from comparative studies with other diaminonaphtalenes in 60percent (v/v) Me2SO-H2O.Studies of the protonation of 1,8-dimorpholino-2,7-dimethoxynaphtalene (pKa 13.0) and 1,8-dimorpholino-2,7-diethoxynaphtalene (pKa 12.5) were made in aqueous sodium hydroxide.The reversible acid-base reactions of the diaminonaphtalenes in the presence of hydroxide ion occur slowly.For example the approach to an equilibrium mixture of the protonated and unprotonated forms of 1,8-bis(diethylamino)-2,7-diethoxynaphtalene in 60percent (v/v) Me2SO-H2O with 0.01 mol dm-3 NaOH occurs with a half-life of 8 s.It is found that 2- and 7-substituents have large effects in increasing the basicity and decreasing the rates of proton transfer and this is due in part to an increase in strain in the amines and in the transition state for proton transfer.
- Hibbert, Frank,Simpson, Gareth R.
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- Ring lithiation of 1,8-bis(dimethylamino)naphthalene: Another side of the 'proton sponge coin'
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It has been found that 1,8-bis(dimethylamino)naphthalene (DMAN), unlike N,N-dimethylaniline, undergoes ring metallation in the n-BuLi-TMEDA-Et2O system with a low selectivity and in poor total yields. The situation is significantly improved in the t-BuLi-TMEDA-n-hexane system when 3- and 4-lithium derivatives become the only reaction products obtained in good yields. The formation of 3-Li-DMAN is especially desired since no method of direct meta-functionalization of DMAN is known to date. The relative stability and structure of DMAN lithium derivatives have been examined with the help of X-ray and multinuclear NMR measurements as well as DFT calculations.
- Antonov, Alexander S.,Pozharskii, Alexander F.,Ozeryanskii, Valery A.,Filarowski, Aleksander,Suponitsky, Kyrill Yu.,Tolstoy, Peter M.,Vovk, Mikhail A.
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p. 17756 - 17766
(2015/10/19)
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- A simple and effective procedure for the N-permethylation of amino-substituted naphthalenes
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A wide range of amino-substituted naphthalenes can be N-permethylated by the system Me2SO4/Na2CO3/ H2O(alcohols) with good to excellent yields. Steric hindrance does not prevent the reaction. Some amines with electron-withdrawing groups, especially at nonconjugated positions, are also alkylated. The procedure allows the combination of a reduction (catalytic or by tin dichloride in acidic media) and a methylation in a one-pot process. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Sorokin, Vladimir I.,Ozeryanskii, Valery A.,Pozharskii, Alexander F.
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p. 496 - 498
(2007/10/03)
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- peri-naphthalenediamines: XXXIV. 1,4,5,8-Tetrakis(dimethylamino)naphthalene: Alternative approaches to synthesis
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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 α-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.
- Sorokin,Ozeryanskii,Pozharskii
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p. 699 - 708
(2007/10/03)
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- peri-Naphthylenediamines 31.* Study of interconversions of 2,3-dihydroperimidines and 1,8-bis(dialkylamino)naphthaienes. Convenient synthesis of 1,2,2,3-tetramethyl-2,3-dihydroperimidine and a monoisopropyl analog of the "proton sponge"
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Efficient procedures were developed for the two-step synthesis of 1,2,2,3-tetramethyl-2,3-dihydroperimidines and for the one-step synthesis of 1,3-dimethyl-2,3-dihydroperimidines starting from 1,8-diaminonaphthalenes. New possibilities of the use of 2,3-dihydroperimidinium salts in the synthesis of 1,8-bis(dialkylamino)naphthalenes ("proton sponges") containing the N-isopropyl group along with the N-methyl groups were demonstrated. The 1,1,2,2,3-pentamethyl-2,3-dihydroperimidinium cation exists in the acyclic iminium form responsible for its high reactivity.
- Ozeryanskii,Filatova,Sorokin,Pozharskii
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p. 846 - 853
(2007/10/03)
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- Vitamin D analogues
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The present invention relates to novel 1α-hydroxy vitamin D derivatives in which the 17-position side chain carries an azide or optionally substituted 1,2,3-triazole group, including compounds of general formula (I) where R1 represents a methyl group having α- or β-configuration; W represents a valence bond or a C1-5 alkylene group; X represents azide or an optionally substituted triazole group; and A=represents a cyclohexylidene moiety characteristic of the A-ring of a 1α-hydroxylated vitamin D or analogue thereof. Active compounds of the invention exhibit cell modulating activity while exhibiting a substantial lack of calcaemic effect. STR1
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- PERI-NAPHTHYLENE DIAMINES III. CONVENIENT METHOD FOR THE ALKYLATION OF 1,8-NAPHTHYLENEDIAMINES AND PERIMIDINES
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In dimethyl sulfoxide or hexamethylphosphorotriamide in the presence of potassium hydroxide 1,8-naphthylenediamine is readily alkylated by an excess of methyl and ethyl iodide to the corresponding 1,8-bis(dialkylamino)naphthalene.Perimidone, which has low basicity, is methylated to 1,3-dimethylperimidone under these conditions.The potassium hydroxide-dimethyl sulfoxide system also secures higher yields of the N-substituted products during the alkylation of perimidine, 2-methylperimidine, and aceperimidine by alkyl halides compared with the potassium hydroxide-alcoholsystem.The yield and structure of the products from benzylation of the perimidines depend on the presence of substituents at position 2 of the heterocyclic system of perimidine.
- Kurasov, L. A.,Posharskii, A. F.,Kuz'menko, V. V.
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p. 1735 - 1738
(2007/10/02)
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- PERI-NAPHTHALENEDIAMINES. II. GENERAL METHOD FOR THE SYNTHESIS OF TETRA-, TRI-, AND DI-N-SUBSTITUTED 1,8-NAPHTHYLENEDIAMINES
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By the action of alkalis or lithium aluminum hydride 1,1,3-trialkyl- and 1,1-dialkyl-3-acetyl-2,3-dihydroperimidinium salts are converted smoothly into di-, tri-, or tetraalkyl-substituted 1,8-naphthylenediamines.If the number of N-ethyl groups in the 1,8-naphtylenediamines is increased, their basicity and the strength of the intramolecular hydrogen bond increases.
- Pozharskii, A. F.,Kurasov, L. A.,Kuz'menko, V. V.,Popova L. L.
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p. 884 - 891
(2007/10/02)
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