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.     

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

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.     

Rearrangements and fragmentations of [C2H5S]+ ions

From deuterium labelling experiments it was concluded that metastable molecular ions of ethyl methyl sulfide lose a methyl radical with the formation of both [CH₃S?CH₂]⁺ amd [CH₃CH?SH]⁺˙ The fragmentation reactions of metastable ions generated with these structure are losses of C₂H₂, H₂S and CH₄. These reactoins and the preceding isomerizations have also been studied by means of deuterium labelling. From the results it is concluded that the three fragmentation reactions most probably occur from ions with a C? C? S skeleton. Appearance energy measurements for ions generated with the two structures above and all give rise to the same ΔH_f value for these three isomeric forms. Ab initio molecular orbitals calculations confirm that these three ions fortuitously have very similar heats of formation. A potential energy diagram rationalizing the isomerizations and the principal fragmentation reaction is presented.     

Reactions within and between adjacent dimethylamino groups: Collision-induced dissociation tandem mass spectrometric study of the 1,9-bis(dimethylamino)phenalenium cation

The electron impact (EI) ionization-induced fragmentation pathways of the new 1,9-bis(dimethylamino) phenalenium cation [1]⁺ were investigated. The peri-dimethylamino substituents of [1]⁺ are incorporated in a trimethine cyanine substructure and show strong steric interactions. A mechanism is proposed for the unusual elimination of CH₃N?CH₂, HN(CH₃)₂ and (CH₃)₃N from [1]⁺ and for the accompanying cyclizations to heterocyclic ions: prior to fragmentation, the intact cation [1]⁺ rearranges, by reciprocal CH₃ and H transfers, to new isomeric cations which decompose subsequently in a characteristic way. A wealth of consistent information on dissociation pathways and fragment structures is provided by collision-induced dissociation tandem mass spectra, collision-induced dissociation mass-analysed ion kinetic energy spectra and exact mass measurements of the salt cation and of its primary fragment ions. The liquid secondary ion mass spectrum of [1]⁺ is very similar to its EI mass spectrum.     

Massenspektrometrische Untersuchungen an Organophosphorverbindungen. II—Elektronenstoßinduzierte Fragmentierungen von Tetraorganodiphosphandisulfiden

The behaviour under electron impact (70 eV) which includes some rearrangement processes of some tetraorganodiphosphanedisulfides R₂P(S)-P(S)R₂ (R ? CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, C₃H₅, C₆H₅) and CH₃RP(S)–P(S)CH₃R (R ? C₂H₅, n-C₃H₇, n-C₄H₉, C₆H₅, C₆H₅, C₆H₅,CH₂) is reported and discussed. Fragmentation patterns which are consistent with direct analysis of daughter ions and defocusing metastable spectra are given. The atomic composition of many of the fragment ions was determined by precise mass measurements. In contrast to compounds R₃P(S) loss of sulphur is not a common process here. The first step in the fragmentation of these compounds is cleavage of one P–C bond and loss of a substituent R?. The second step is elimination of RPS leading to [R₂PS]⁺ from which the base peaks in nearly all the spectra arise. The phenyl substituted compounds give spectra with very abundant [(C₆H₅)₃P]^+. and [(C₆H₅)₂CH₃P]^+. ions respectively, resulting from [M]^+. by migration of C₆H₅. Rearrangement of [M]^+. to a 4-membered P-S ring system prior to fragmentation is suggested.     

Hydrogen-carbon,carbon-carbon double rearrangement induced by proximity effects. 1–formation of methoxybenzyl ions in the electron impact mass spectra of substituted 1,1-bis(dimethoxyphenyl)methanes

The 75 eV electron impact mass spectra of 1,1-bis(dimethoxyphenyl)methanes bearing o-methoxy groups are dominated by intense peaks corresponding, at least formally, to benzyl ions [(CH₃O)₂C₆H₃CH₂]⁺ (b). They arise from ions [((CH₃O)₂C₆H₃)₂CH]⁺ (a), which are in turn formed from molecular ions by loss of an alkyl radical through benzylic cleavage. The analysis of compounds labelled with ²H or ¹³C at methoxy groups led to the determination of the mechanism. Hydrogen migration, as hydride, followed by electrophilic substitution by the methylene carbon of the phenyl methylene ether cation through a six-centred transition state is responsible for the formation of benzylic ions b.     

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.     

New Heterocyclic Organophosphorus–Sulfur–Nitrogen Compounds,Syntheses and Structures

The new compound C₁₀H₆P(S)[NSi(CH₃)₃]₂P(S) ( 3 ) which contains a P₂N₂ heterocycle has been prepared in low yield by partial thermal decomposition of 1-{[N,N′-bis(trimethylsilyl)acetamidinium]sulfido}-3-(trimethylsilylamino)-1 H,3 H,1 λ⁵,3 λ⁵-naphtho[1,8 a,8-cd][1,2,6]thiadiphosphinine-1,3-dithione [CH₃C{NHSi(CH₃)₃}₂]⁺[C₁₀H₆P(S)(NHSiMe₃)SP(S)₂]^– ( 2 ). Reaction of 2 with potassium hydroxide in acetonitrile gives the completely desilylated product [CH₃C(NH₂)₂]⁺[C₁₀H₆P(S)(NH₂)SP(S)₂]^– ( 4 ). The structures of the new compounds 3 and 4 were elucidated by FTIR and NMR spectroscopy methods and by X-ray structure analyses.     

Mass spectrometric study of 2-azafluorenes

The fragmentation of 2-azafluorene and its methyl and phenyl-substituted derivatives was studied. It is shown that ejection of an RCN fragment (R=CH₃, C₆H₅) by the molecular ions leads to a more intense peak if R is in the 3 position of the azafluorene ring. It was established that, in contrast to the dissociative ionization of fluorene, all of the ions of which are formed from the (M-H)⁺ fragment, the fragmentation of 2-azafluorene and its derivative also takes place from the molecular ion. Randomization of the deuterium atoms attached to C₉ with the remaining hydrogen atoms was observed.Translated from Khimiya Geterotisiklicheskikh Soedinenii, No. 1, pp. 101–105, January, 1977.     

Metastable ion and induced stable ion fragmentation of isomeric 5-methyl-3-tolyl-1,2,4-oxadiazoles

The electron ionization fragmentation patterns of 5-methyl-3-(o-, m- and p-tolyl)-1,2,4-oxadiazoles (1a—c) have been examined by metastable ion and high resolution mass spectrometry. The o-tolyl isomer loses CO and C₂H₂O from the metastable molecular ion whereas the m- and p-tolyl isomers lose only CH₃CN thus indicating a strong ortho effect in directing the fragmentation in 1a. Slight differences between o-, m- and p-tolyl isomers in the collisional activation fragmentation of stable [C₇H₆N]⁺ ions suggest that structural differences exist even after a series of extensive rearrangements of the molecular ions. Metastable ion kinetic energy (MIKE) and collisional activation (CA) spectra were very helpful in providing valuable information about many fragments.     

An energy-resolved study of the fragmentation of ionized 1-Penten-3-ol

A detailed energy-resolved study of the fragmentation of CH₂?CHCH(OH)CD₂CD₃ (1-d₅) has been carried out using metastable ion studies and charge exchange techniques, combined with collision-induced dissociation studies to establish the structures of fragment ions. At low internal energies (metastable ions) the molecular ion of 1-d₅ rearranges to the 3-pentanone structure and fragments by loss of C₂H₅ or C₂D₅ leading to the acyl structure, [CH₃CH₂C?O]⁺ or [CD₃CD₂C?O]⁺, for the fragment ion. However, with increasing internal energy of the molecular ion this rearrangement process decreases rapidly in importance and loss of C₂D₅ by direct cleavage, leading to [CH₂?CHCH?OH]⁺, becomes the dominant fragmentation reaction. As a result the [C₃H₅O]⁺ ion seen in the electron impact mass spectrum of 1-penten-3-ol has predominantly the protonated acrolein structure.     

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.     

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.     

Mass spectra of organometallic compounds: XIV—Some monometallic olefing manganese tricarbonyl derivatives

The metastable ion supported fragmentation process in the mass spectra of the cyclohexadienyl derivative C₆H₇Mn(CO)₃, the cycloheptadienyl derivative C₇H₉Mn(CO)₃, the 1,2,3,4,5-and 1,2,3,5,6-pentahaptocyclootadienyl derivatives C₈H₁₁Mn(CO)₃, the cyclooctatrienyl derivative C₈H₉Mn(CO)₃ and the substituted cyclopentadienyl derivative (CH₃)₂NCH₂C₅H₄Mn(CO)₃, are described. Losses of carbonyl groups, generally stepwise, from the molecular ions to give the corresponding [M – 3CO]⁺· ions are first observed. Further fragmentation of the carbonyl-free [M – 3CO]⁺· ions can involve a variety of processes such as the following: (a) elimination of a neutral manganese atom to give a hydrocarbon fragment; (b) elimination of a neutral hydrocarbon fragment to give an [MnH]⁺· ion; (c) dehydrogenation; (d) elimination of a 2-carbon C₂H₂ or C₂H₄ fragment; (e) elimination of a C₃H₄ or C₃H₆ fragment as a neutral species when it is bridging two carbon atoms bonded to manganese, as in C₈H₉Mn(CO)₃ and 1,2,3,4,5,h⁵-C₈H₁₁Mn(CO)₃, respectively. Fragmentation of the [M – 3CO]⁺· ion in (CH₃)₂NCH₂C₅H₄Mn(CO)₃ presents the following additional features: (a) elimination of C₆H₆ with a nitrogen shift from carbon to manganese; (b) elimination of a neutral dimethylamino fragment to give [C₆H₆Mn]⁺·, which then loses neutral C₆H₆, C₆H₅ or Mn fragments and thus is formulated tentatively as [(fulvene)Mn]⁺· or [C₆H₅MnH]⁺· rather than [(benzene)Mn]⁺·.     

The potential energy surface for the [C2H2O]+˙ system: The ketene radical cation [CH2CO]+˙ and its isomers

Ab initio molecular orbital calculations with large, polarization basis sets and incorporating valence electron correlation have been employed to examine the [C₂H₂O]^+˙ potential energy surface. Four [C₂H₂O]^+˙ isomers have been identified as potentially stable, observable ions. These are the experimentally well-known ketene radical cation, [CH₂?C?O]^+˙ (a), and the presently unknown ethynol radical cation, [CH₂?C? OH]^+˙ (b), the oxirene radical cation (c) and an ion resembling a complex of CO with [CH₂]^+˙, (d). The calculated energies of b, c and d relative to a are 189, 257 and 259 kJ mol^?1, respectively. Dissociation of ions a and d is found to occur without reverse activation energy.     

Mass spectrometry of transition metal π-complexes. XV—The effect of substituents on the fragmentation of benchrotrenyls under electron impact

Mass spectra of substituted benchrotrenyls RC₆H₅Cr(CO)₃ where R?H, F, CI, I, CH₃, OCH₃, COOCH₃, C₂H₅, N(CH₃)₂, NH₂, C₆H₅, C(CH₃)₃, p-C₆H₄NH₂, CH₂C₆H₅, CH₂CH₂C₆H₅), 1,3,5-(CH₃)₃C₆H₃Cr(CO)₃ and 1,2,3,5-(CH₃)₄C₆H₂Cr(CO)₃ have been studied. It has been found that for monosubstituted benchrotrenyls there is a linear dependence of the parameter log [Cr]⁺/[RC₆H₅Cr]⁺) on the number of degrees of freedom of the [RC₆H₅Cr]⁺ ion. Decarbonylation of the molecular ions is not affected by the nature of the substituent R. The results are interpreted in terms of the quasi-equilibrium theory of mass spectra.     

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.     

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.     

Fragmentation of pyrazolecarbaldehyde thio- and dithioacetals under electron impact and chemical ionization

The mass spectra of 1-substituted 3,5-dimethyl-1H-pyrazole-4-carbaldehyde bis(2-hydroxyethyl) dithioacetals and thioacetals were studied for the first time. The main fragmentation pathways of their molecular ions generated under electron impact and chemical ionization were similar. Primary decomposition of the molecular ions of bis(2-hydroxyethyl) dithioacetals involves elimination of 2-sulfanylethanol molecule with formation of the corresponding 1,3-oxathiolane radical cation. Fragmentation of the molecular ions [M]⁺ · and [M + H]⁺ derived from 2-(3,5-dimethyl-1H-pyrazol-4-yl)-1,4,6-oxadithiocanes includes cleavage of the eight-membered heteroring and elimination of C₄H₉OS ·. Substituents in the heteroring of pyrazolecarbaldehydes inhibit decomposition processes related to the aldehyde group.