peri-Naphthylenediamines. 35. Unusual behavior of “proton sponge”-derived Mannich bases

Aminomethylation of 1,8-bis(dimethylamino)naphthalene (proton sponge) afforded a series of its 4-dialkylaminomethyl-substituted derivatives. An attempt to introduce the second peri-dialkylaminomethyl group unexpectedly led to the formation of salts with the 2,2-dialkyl-6,7-bis(dimethylamino)-2-azonia-2,3-dihydrophenalene cation. The structure of one of these salts was established by X-ray diffraction analysis. Treatment of 1,8-bis(dimethylamino)-4-piperidinomethylnaphthalene with iodomethane gave a spiro compound rather than the expected N-[4,5-bis(dimethylamino)-1-naphthylmethyl]-N-methylpiperidinium iodide. This spiro compound was generated through cyclodimerization of the 1-naphthylmethyl carbocations. These transformations provide evidence that proton sponge-derived Mannich bases quaternized at the dialkylaminomethyl group are unstable and undergo the spontaneous transformation into the resonance-stabilized 4,5-bis(dimethylamino)-1-naphthylmethyl carbocation. By contrast, 4-dialkylamino-1-dimethylaminomethylnaphthalenes gave methoiodides, which are stable under standard conditions. The latter compounds undergo the nucleophilic substitution of the NR₃ group typical of such salts.     

peri-naphthylenediamines

First indirect evidence for the formation of a radical cation of 1,8-bis(dimethylamino)naphthalene (“proton sponge”) in reactions with HNO₃, HNO₂, NO₂, and I₂ has been obtained. In all cases, the products of reaction of the radical cation with nucleophiles and/or its dimer, 4,5,4′,5′-tetrakis(dimethylamino)-1,1′-binaphthyl, have been isolated. 4-Chloro-1,8-bis(dimethylamino)naphthalene has been regioselectively synthesized in high yield. For Part 24, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 320–324, February, 1998.     

peri-Naphthylenediamines

Tertiary alcohols containing the 4,5-bis(dimethylamino)-1-naphthyl group were synthesized. The carbocations that formed from α-methyl-containing alcohols in an acidic medium underwent smooth El elimination to give the corresponding unsaturated derivatives of the “proton sponge” in good yields. At the same time, the carbocation generated from 4-(α-hydroxybenzhydryl)-1,8-bis(dimethylamino)naphthalene was converted into a benzo-[a]fluorene derivative as a result of a complex reaction which has been previously unknown in the chemistry of “proton sponges.” The structure of the latter derivative was established by X-ray diffraction analysis. For Part 26, see Ref. 1; this paper simultaneously presents Part 5 of the series “Resonance-stabilized α-naphthylmethyl carbocations and derived spiro compounds;” for Part 4, see Ref. 2. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1103–1108, June, 2000.     

peri-Naphthylenediamines

The reaction of 1,8-bis(dimethylamino)naphthalene (“proton sponge”) with trifluoroacetic anhydride afforded new derivatives of naphtho[1,8-c,d]pyran,viz., trans-) (4) andcis-1,3-dihydroxy-6,7-bis(dimethylamino)-1,3-bis(trifluoromethyl)-1H,3H-naphthol[1,8-c,d]pyran (5) and symmetrical 3,4,10,11-tetrakis(dimethylamino)-7,14-bis(trifluoromethyl)-7,14-epoxydinaphtho[1,8-a,b;1′, 8′-ef]cyclooctane (3), which belongs to a new type of double “proton sponges,” along with the expected 1,8-bis(dimethylamino)-4-trifluoroacetylnaphthalene. The structures of compounds3 and4 were established by spectral studies and X-ray diffraction analysis.     

peri-Naphthylenediamines

Catalytic hydrogenation of 1,8-bis(dimethylamino)-2-nitronaphthalene afforded previously unknown 2-amino-1,8-bis(dimethylamino)naphthalene. ItsN-acetyl derivative and 1,2,8-tris(dimethylamino)naphthalene were prepared. The pK _a ¹ values of the 2-NH₂-, 2-NHAc-, and 2-NMe₂-substituted “proton sponges” determined by a competition method in DMSO are equal to 10.3, 7.5, and 9.0, respectively.     

peri-naphthylenediamines

meta-Substituted “proton sponges” were prepared for the first time by the direct nitration of 5,6-bis(dimethylamino)acenaphthene under strong acidic conditions and by the selective reduction of 1.3,8-tri- and 1,3,6,8-tetranitronaphthalenes and subsequent alkylation of the compounds obtained. 4,5-Bis(dimethylamino)-1,2,3,6,7,8-hexanitronaphthalene was synthesized starting from 1,3,6,8-tetranitronaphthalene. For Part 28, see Ref. 1. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 8, pp. 1405–1411, August, 2000.     

peri-Naphthylenediamines

4,5,4′,5′-Tetrakis(dimethylamino)-1,1′-binaphthalene, unknown previously, was obtained in ∼20% yield by the oxidation of 1,8-bis(dimethylamino)naphthalene with Tl(OAc)₃ or Pb(OAc)₄ at low temperatures. Treatment of the reaction product with excess Li and then with O₂ gave, depending on the reaction temperature, perylene or 4,4′-bis(dimethylamino)-1,1′-binaphthalene in good yields, instead of expected 3,4,9,10-tetrakis(dimethyl-amino)perylene. For Part 23, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 93–98, January, 1998.     

peri-Naphthylenediamines 18. 1,8-Bis(dimethylamino)-4-vinylnaphthalene

The 1-[1,8-bis(dimethylamino)-4-naphthyl[ethyl carbocation generated from the corresponding alcohol in benzene in the presence of Al₂O₃ undergoes elimination according to theE1 mechanism to give previously unknown 1,8-bis(dimethylami no)-4-vinyl naphthalene in a good yield. This compound was also synthesized from 1,8-bis(dimethylamino)-4-formylnaphthalene by the Wittig reaction. Polymerization of the vinylic derivative obtained was studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2297–2300, September, 1996.     

Oxidation of 1-amino-4,5-bis(dimethylamino)naphthalene as a route to the double ��proton sponges�� based on dibenzo[a,h]phenazine and 1,1��-azonaphthalene

Behavior of 4-amino-1-dimethylamino- and 1-amino-4,5-bis(dimethylamino)naphthalenes sharply differs on their treatment with tosyl chloride and oxidation with the Bu^tOK/O₂ system. While the former upon the action of tosyl chloride in protic media is transformed to sulfonamide, the latter unexpectedly forms 4,5,11,12-tetrakis(dimethylamino)dibenzo[a,h]phenazine in ??20% yield as a product of the competitive reaction, which represents the earlier unknown type of double ??proton sponges??. In contrast to this, the oxidative dimerization of the indicated amines with Bu^tOK/O₂ leads to 5,12-bis(dimethylamino)dibenzo[a,h]phenazine and 4,5,4??,5??-tetrakis(dimethylamino)-1,1??-azonaphthalene, respectively. Possible mechanisms of these reactions were considered, as well as problems of coloring, solvatochromism, and protonation of the compounds obtained.     

peri-Naphthylenediamines. 32. Reactions of 4,5-bis(dimethylamino)-1-naphthyllithium and 4,5-bis(dimethylamino)-1-naphthylmagnesium bromide with electrophilic agents. New representatives of double naphthalene “proton sponges” with the structures of 1,1"-binaphthyl ketone and 1,1"-binaphthylmethanol

The 4-deuterio, 4-methyl, 4-iodo, 4-methylthio, 4-trimethylsilyl, and 4-ethoxycarbonyl derivatives of 1,8-bis(dimethylamino)naphthalene (proton sponge) and some related alcohols were prepared by the reactions of 4,5-bis(dimethylamino)-1-naphthyllithium or 4,5-bis(dimethylamino)-1-naphthylmagnesium bromide with the corresponding electrophilic reagents. New representatives of double proton sponges with the structures of 1,1"-binaphthyl ketone and 1,1"-binaphthylmethanol were synthesized. The pK _a values of selected compounds in DMSO were measured by competitive protonation.     

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.     

Polyphenols and acids of Ulugbekia tschimganica

From the herbage ofUlugbekia tschimganica (B. Fedtsch.) Zak two new phenolcarboxylic acids have been isolated in the form of their methyl derivatives: methyl ulugbekate C₁₉H₁₈O₆ (I) and methyl ulugbinate acid C₂₀H₂₂O₇ (II), mp 228°C. It has been established that (I) most probably has the structure of 1,5-bis(3′,4′-dihydroxyphenyl)-3-methoxycarbonylpent-1-ene and (II) that of 1,5-bis(2′,4′-dihydroxyphenyl)-3-methoxycarbonylpent-1-ene and (II) that of 1,5-bis(2′,4′-dihydroxyphenyl)-3-methoxycarbonyl-4-methoxypent-2-ene.     

peri-Naphthylenediamines

Catalytic hydrogenation of 4-nitro-1,8-bis(dimethylamino)naphthalene afforded the previously unknown 1-amino-4,5-bis(dimethylamino)naphthalene, subsequent methylation of which gave 1-methylamino and 1-dimethylamino “proton sponge” derivatives. The pK _a values of 1-amino-, 1-methylamino-, and 1-dimethylamino-4,5-bis(dimethylamino)-naphthalenes estimated by¹H NMR in DMSO-d₆ are equal to 9.8, 10.1, and 8.0, respectively.     

2,3-Epoxyperfluoro-2-methylpentane in reactions with urea and thiourea

2,3-Epoxyperfluoro-2-methylpentane reacts with thiourea in protic (methanol, 2-propanol) and aprotic (dioxane) solvents, and also with urea in acetonitrile affording unexpected products: 1-(2,2,3,3,3-pentafluoropropionyl)-2-(2,2,2-trifluoro-1-trifluoro-methylethyl)isothiourea, and 1-(2,2,3,3,3-pentafluoropropionyl)-3-(2,2,2-trifluoro-1-trifluoro-methylethyl)urea respectively that result from the rearrangement of the intermediately formed ketone in the process of the intramolecular “haloform” cleavage. At the same time in dioxane the 2,3-epoxyperfluoro-2-methylpentane reacts with urea with the formation of a heterocyclic compound, 2-amino-4-pentafluoroethyl-5,5-bis(trifluoromethyl)-4,5-dihydrooxazol-4-ol. From 1-(2,2,3,3,3-pentafluoropropionyl)-2-(2,2,2-trifluoro-1-trifluoromethylethyl)isothiourea and Cu(OAc)₂ a stable fluorine-containing chelate complex was obtained.     

Reactions ofn-hexane andn-nonane on Pt catalysts and hydrogenating off hydrocarbonaceous adspecies after reaction

n-Hexane andn-nonane were reacted on Pt black, 6% Pt/SiO₂, 0.8% Pt/KL zeolite and a 0.6% industrial Pt/Al₂O₃ catalyst. Selectivities were compared at ∼10% conversion. After reaction, the catalyst was exposed to H₂ and the hydrocarbons leaving the catalysts were analyzed. The amount of hydrocarbons left the catalysts decreased in the sequence Pt black>Pt/SiO₂>Pt/KL>Pt/Al₂O₃. The composition of removed hydrocarbons gave important—although indirect—information on the possible state of “hydrocarbonaceous deposits” during catalysis.     

Co<Superscript>II</Superscript> and Rh<Superscript>I</Superscript> complexes with <Emphasis Type="Italic">C</Emphasis><Subscript>2</Subscript>-symmetric chiral diamines of the dioxolane series

The reaction of di-μ-chlorobis(1,5-cyclooctadiene)dirhodium with (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane (1) gave the complex [Rh(cod)(1)]Cl (cod is 1,5-cyclooctadiene). The composition of the complexes CoCl₂ · L₂ and [Rh(cod)(L₂)]X (L₂ = 1, (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane; X = Cl, TfO) was studied using IR and ¹H NMR spectroscopy. In the Rh^I cyclooctadienediamine complexes, the diene molecule forms a stronger bond with the metal atom than that in the cyclooctadienediphosphine analogs. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2270–2274, October, 2005.     

Two-step α-ureidoalkylation of ureas with 4,5-dihydroxyimidazolidin-2-ones

Two-step α-ureidoalkylation of ureas with various 4,5-dihydroxyimidazolidin-2-ones gave novel 1,3-dialkyl-4,5-bis(3-alkylureido)-, 1,3-dialkyl-4,5-bis[3-(2-pyrimidyl)ureido]-, or 1,3-dialkyl-4,5-bis(3,3-dialkylureido)imidazolidin-2-ones and ensembles of three imidazolidine rings. The structure of 4,5-bis(2-oxoimidazolidin-1-yl)imidazolidin-2-one was confirmed by X-ray diffraction data. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 140–145, January, 2007.     

peri-Naphthylenediamines. 38. Naphthalene and acenaphthene “proton sponges” with +M substituents in ortho positions with respect to peri-dimethylamino groups

Previously unknown 4,5,6,7-tetrakis(dimethylamino)acenaphthene, which is the first acenaphthene derivative containing four vicinal dialkylamino groups, was synthesized based on 5,6-bis(dimethylamino)-4,7-dinitroacenaphthene. The total synthesis of 1,2,7,8-tetrakis(dimethylamino)naphthalene was carried out starting from 3,6-dinitronaphthalic anhydride. Other proton sponges of this type, viz., 1,7,8-tris(dimethylamino)-2-methoxy- and 1,8-bis(dimethylamino)-2,7-dipiperidinonaphthalenes, were prepared by the nucleophilic substitution in 2,7-dimethoxy-1,8-dinitronaphthalene. In solutions, 1,2,7,8-tetrakis(dimethylamino)naphthalene and its analogs can form di- and trications in the presence of acids. The basicity constants pK _a ¹ of the compounds measured in DMSO depend in a complex way on their structures but correlate with the basicity index B, which is determined by changes in the chemical shifts _H after the addition of the first proton. Due to low C-nucleophilicity of ortho-disubstituted proton sponges in combination with high basicity, these compounds hold considerable promise as reagents in organic synthesis.     

Sol-Gel Microsphere Pelletisation Process for Fabrication of (U,Pu)O2, (U,Pu)C and (U,Pu)N Fuel Pellets for the Prototype Fast Breeder Reactor in India

A “dust-free” sol-gel microsphere pelletisation (SGMP) process has been developed for fabrication of (U,Pu)O₂, (U,Pu)C and (U,Pu)N fuel pellets containing around 15% plutonium for the forthcoming prototype fast breeder reactor (PFBR) in India. The objective was to produce homogeneous sintered pellets of ∼85% T.D. with a predominantly open-pore structure. Hydrated gel-microspheres of UO₃+PuO₂ and UO₃+PuO₂+C have been prepared from nitrate solutions of uranium and plutonium by the “ammonia internal gelation” process, using hexamethylene tetramine (HMTA) as an ammonia generator and silicone oil at 90±1°C as gelation bath. For oxide fuel pellets, the hydrated UO₃+PuO₂ gel-microspheres were calcined at around 700°C in Ar+8% H₂ atmosphere to produce “non-porous”, “free-flowing” and coarse (around 400 micron) microspheres which could be directly pelletised at 550 MPa to green pellets. The mixed oxide pellets were subjected either to low temperature (∼1100°C) oxidative sintering (LTS) in N₂+air containing ∼1500 ppm O₂ or to high temperature (1650°C) sintering, (HTS) in Ar+8% H₂. For monocarbide and mononitride pellets, hydrated gel-microspheres of UO₃+PuO₂+C were subjected to carbothermic synthesis in vacuum (∼1 Pa) and flowing nitrogen (flow rate: 1.2 m³/h) in the temperature range of 1450–1550°C respectively. The monocarbide and mononitride microspheres thus produced were relatively hard and required higher compaction pressure (∼1200 MPa) for making reen pellets which could be sintered to 85% T.D. in Ar+8% H₂ at 1700°C. The sintered oxide, monocarbide and mononitride pellets had a “blackberry” “open” pore microstructure with fine grain size. The microspheres retained their individual identity in the sintered pellets because during sintering densification took place mainly within and not between the microspheres.     

Borohydride reduction of acetophenone and esters of dehydrocarboxylic acids in the presence of chiral cobalt(<Emphasis Type="SmallCaps">II</Emphasis>) diamine complexes

The catalytic reduction of acetophenone, methyl α-acetamidocinnamate, and dimethyl itaconate with alcohol-modified sodium borohydride was studied in the presence of complexes CoCl₂·L₂ (L₂ are chiral C ₂-symmetric diamines: (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(diphenylaminomethyl)-1,3-dioxolane). The maximum enantiomeric excess of (S)-1-phenylethanol was 24%, that of dimethyl α-methylsuccinate was 38%.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 342–347, February, 2005.