Synthesis and Diels-Alder Reactivity of 5,6,7,8-Tetramethylidene-2-bicyclo[2.2.2]octanol and -octanone. Selective Oxidations of the Corresponding Bis(irontricarbonyl) Complexes

Hydroboration of the syn, anti-[Fe(CO)₃]₂ double complex 24 of the readily available 5,6,7,8-tetramethylidene-2-bicyclo[2.2.2]octene ( 22 ) gave the corresponding doubly complexed 2-bicyclo[2.2.2]octanol 25. CrO₃-oxidation furnished ketone 27 . The syn-Fe(CO)₃-groups in 25 and 27 were oxidized selectively with trimethyl-amine oxide and yielded the corresponding anti-Fe(CO₃)-monocomplexed tetraenes 26 and 28. The anti-Fe(CO)₃-group in 28 could be removed, and 5,6,7,8-tetramethylidene-2-bicyclo[2.2.2]octanone ( 11 ) was obtained. NaBH₄-reduction of 11 afforded tetraenol 10. TCE-cycloadditions to 10 and 11 (k₁) were at least 10 times as fast as those (k₂) to the corresponding monoadducts 35/36 and 34 , respectively. This Diels-Alder reactivity difference vanishes (k₁ ≈ k₂) with methyl propynoate. The latter dienophile added to the anti-Fe(CO)₃-monocomplexed tetraenone 28 with ‘para’-regioselectivity.     

Studies on sulfinatodehalogenation. XX. Sodium dithionite-initiated addition of per- and polyfluoroalkyl iodides to cyclic enol ethers and chemical conversions of the products

Per- and polyfluoroalkyl iodides [R_FI, R_F=Cl(CF₂)₄, 1a ; Cl(CF₂)₆, 1b ; Cl(CF₂)₈, 1c ; n-C₆F₁₃, 1d ; n-C₈F₁₇, 1e ] reacted with cyclic enol ethers such as 2,3-dihydrofuran (2) and 3,4-dihydro-2H-pyran (3) in aqueous acetonitrile in the presence of sodium dithionite and sodium bicarbonate at room temperature (10–15°C) to give the corresponding 2-(F-alkyl) hemiacetals in high yields. The adducts were oxidized with Ce(NH₄)₂(NO₃)₆ in acetonitrile or reduced with LiAlH₄ in ether to form the corresponding 2-(F-alkyl)lactones or diols respectively in good yields. In the presence of p-toluenesulfonic acid, the adducts were refluxed in benzene and CH₃CN to produce the corresponding 2,3-dihydro-4-(F-alkyl) furan and 3,4-dihydro-5-(F-alkyl)-2H-pyran. This is a new and effective method for preparing these useful organofluorine compounds.     

Small Chains of Main Group Elements by BH3 Adduct Formation of tBu2E-N(H)-EtBu2 (E = P,As)

Borane adducts of bis(di-tert-butylphosphanyl)amine ( 1a ) and bis(di-tert-butylarsino)amine ( 1b ) are reported. Based on quantum-chemical investigations in combination with experimental results, it is demonstrated that the tautomerism known for tBu₂P-N(H)-PtBu₂ ( 1a ), can be observed for the mono adduct tBu₂P-N(H)-P(BH₃)tBu₂ ( 2a ) as well, whereas for the corresponding arsenic compound 2b only one stable isomer is found. The bis-borane adduct tBu₂(BH₃)As-N(H)-As(BH₃)tBu₂ ( 3b ) is a rare example of a structurally characterized, tertiary arsine borane adduct, which can be directly compared with the corresponding phosphorus compound tBu₂(BH₃)P-N(H)-P(BH₃)tBu₂ ( 3a ). Deprotonation of mixtures containing 2a by nBuLi leads to the lithium-containing coordination polymer 4a , in which the actual chain consists only of non-carbon atoms.     

Beiträge zur Chemie des Phosphors. 105. 1,2,3,4-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphan und 1,2,3,4-Tetraphenyltetraphosphan

Contributions to the Chemistry of Phosphorus. 105. 1,2,34-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphane and 1,2,3,4-Tetraphenyltetraphosphane 1,2,3,4-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphane, Me₃Si? (PPh)₄? SiMe₃ ( 1 ), is obtained by reacting K₂(PPh)₄ with trimethylchlorosilane under suitable conditions. Compound 1 disproportionates almost easier than the corresponding triphosphane (Me₃Si)₂(PPH)₃. Of the six possible diastereomers only 1a (erythro, meso, erythro), 1b (erythro, d,l, erythro), 1 d (threo, d,l, threo), and 1 f (erythro, threo, threo) can be detected in solution by ³¹P-NMR spectroscopy. In consequence of rapid inversion at the P atoms a dynamic equilibrium exists between the different isomers. The assignment of the ³¹P-NMR-spectroscopically observed spin systems to the corresponding diastereomers results from the dependence of the ¹J_PP-coupling constants on the dihedral angle between vicinal free electron pairs as well as on the observed frequency distribution. In the alcoholysis of 1 the corresponding hydride H? (PPh)₄? H ( 2 ) is formed as the main product. It could be isolated in spite of its instability. At room temperature 2 disproportionates rapidly forming mainly (PPh)₄ and H₂(PPh)₂ (ratio 1:2) at first; later on also H₂(PPh)₃, H₂PPh, and (PPh)₅ are found. The corresponding rearrangements follow a four-center mechanism involving predominantly P? P bonds.     

Nonparameterized MO calculations of ligand-bridged M2(CO)8-(U2-X)2-type dimers containing metal---metal interactions: Evidence for dictation of stereochemistry by one-electron and two-electron metal---metal σ-type bonds

Nonparameterized MO calculations performed on the (edge-bridged)-bioctahedral metal dimers of the Dessy-characterized [Cr₂(CO)₈(μ₂-PR₂)₂]^(n-2) series and of the [Mn₂(CO)₈(μ₂-PR₂)₂]ⁿ series (n = 0, +1, +2) have revealed that the corresponding dimeric pairs with n = 0, +1, and +2 have two, one, and no electrons, respectively, in the antibonding 2b_3u MO corresponding to a “net” no-electron metal---metal bond, a “net” one-electron metal---metal bond, and a two electron metal---metal bond. Of prime significance is that this 2b_3u MO, which is the LUMO in both electron-pair (metal---metal)-bonded dimers (n = +2) and the HOMO in the corresponding dimers to which one or two electrons have been added, is found to be largely composed of in-plane antibonding σ-type dimetal orbital character rather than either out-of-plane π-type dimetal antibonding orbital character or bridging-ligand orbital character. These MO results are also shown to be completely compatible with the available spectral and X-ray data.     

Die Oxidation von 3-(1-Nitro-2-oxocycloalkyl)propanal

The Oxidation of 3-(1-Nitro-2-oxocycloalkyl)propanal Oxidation of the title compound 1 with KMnO₄ under neutral conditions led to the corresponding acid 2 , 5-(2,3,4,5-tetrahydro-2-nitro-5-oxo-2-furyl)pentanoic acid ( 4 ), and 4-oxononadioic acid ( 6 ). On the basis of experimental results the mechanism of the formation of 4 is discussed (Scheme 1). Oxidation of 1 with KMnO₄ under basic conditions gave 6 which was transformed to (E)-4,5-dihydro-5(2′-oxocyclopentyliden)furan-2(3H)-one ( 12 ) with benzene/TsOH (Scheme 3). In contrast to this result the corresponding 4-oxoheptandioic acid ( 22 ) yields 1,6-dioxaspiro[4,4]nonan-2,7-dione ( 23 ) only (Scheme 4).     

Synthetic,Spectroscopic and Structural Studies of the Rhenium(I) Dicarbonyl Complexes of Phosphite,Phosphonite, and Phosphinite Ligands: cis,mer‐[ReBr(CO)2{PPh3‐n(OR)n}3] (R = Me,Et; n = 1—3)

The reaction of [ReBr(CO)₅] with phosphite and phosphonite ligands in toluene yielded cis, mer‐[ReBr(CO)₂L₃] ( 2 : L = P(OMe)₃ 2a : P(OEt)₃ 2b : PPh(OMe)₂ 2c : PPh(OEt)₂ 2d ). Compounds 2c and 2d were also obtained, as were the phosphinite complexes 2e [L = PPh₂(OMe)] and 2f [L = PPh₂(OEt)], by reaction of the corresponding phosphorus ligand with trans, mer‐[ReBr(CO)₃L₂]. Compounds 2 were all characterized by elemental analysis, mass spectrometry and NMR spectroscopy, and the structures of 2b , 2c and 2d were determined by X‐ray diffractometry. Compounds 2a‐d are stable in chloroform and dichloromethane, but 2e and 2f are transformed into the corresponding trans, mer‐[ReBr(CO)₃L₂] complexes by a reaction for which a partial mechanism is put forward.     

Alkoxy-1,3,5-triazapentadien(e/ato) copper(II) complexes: template formation and applications for the preparation of pyrimidines and as catalysts for oxidation of alcohols to carbonyl products

Template combination of copper acetate (Cu(AcO)₂?H₂O) with sodium dicyanamide (NaN(C≡N)₂, 2 equiv) or cyanoguanidine (N≡CNHC(=NH)NH₂, 2 equiv) and an alcohol ROH (used also as solvent) leads to the neutral copper(II)–(2,4‐alkoxy‐1,3,5‐triazapentadienato) complexes [Cu{NH?C(OR)NC(OR)?NH}₂] (R=Me ( 1 ), Et ( 2 ), nPr ( 3 ), iPr ( 4 ), CH₂CH₂OCH₃ ( 5 )) or cationic copper(II)–(2‐alkoxy‐4‐amino‐1,3,5‐triazapentadiene) complexes [Cu{NH?C(OR)NHC(NH₂)?NH}₂](AcO)₂ (R=Me ( 6 ), Et ( 7 ), nPr ( 8 ), nBu ( 9 ), CH₂CH₂OCH₃ ( 10 )), respectively. Several intermediates of this reaction were isolated and a pathway was proposed. The deprotonation of 6 – 10 with NaOH allows their transformation to the corresponding neutral triazapentadienates [Cu{NH?C(OR)NC(NH₂)?NH}₂] 11 – 15 . Reaction of 11 , 12 or 15 with acetyl acetone (MeC(?O)CH₂C(?O)Me) leads to liberation of the corresponding pyrimidines NC(Me)CHC(Me)NC NHC(?NH)OR, whereas the same treatment of the cationic complexes 6 , 7 or 10 allows the corresponding metal‐free triazapentadiene salts {NH₂C(OR)?NC(NH₂)?NH₂}(OAc) to be isolated. The alkoxy‐1,3,5‐triazapentadiene/ato copper(II) complexes have been applied as efficient catalysts for the TEMPO radical‐mediated mild aerobic oxidation of alcohols to the corresponding aldehydes (molar yields of aldehydes of up to 100 % with >99 % selectivity) and for the solvent‐free microwave‐assisted synthesis of ketones from secondary alcohols with tert‐butylhydroperoxide as oxidant (yields of up to 97 %, turnover numbers of up to 485 and turnover frequencies of up to 1170 h^?1).     

New Results in the Synthesis of Styrylazulene Derivatives: Application of the ‘Anil synthesis’ to the preparation of azulenes substituted with styryl groups at the seven-membered ring

The synthesis of 4,6,8-trimethyl-1-[(E)-4-R-styryl]azulenes 5 (R=H, MeO, Cl) has been performed by Wittig reaction of 4,6,8-trimethylazulene-1-carbaldehyde ( 1 ) and the corresponding 4-(R-benzyl)(triphenyl)phosphonium chlorides 4 in the presence of EtONa/EtOH in boiling toluene (see Table 1). In the same way, guaiazulene-3-carbaldehyde ( 2 ) as well as dihydrolactaroviolin ( 3 ) yielded with 4a the corresponding styrylazulenes 6 and 7 , respectively (see Table 1). It has been found that 1 and 4b yield, in competition to the Wittig reaction, alkylation products, namely 8 and 9 , respectively (cf. Scheme 1). The reaction of 4,6,8-trimethylazulene ( 10 ) with 4b in toluene showed that azulenes can, indeed, be easily alkylated with the phosphonium salt 4b . 4,6,8-Trimethylazulene-2-carbaldehyde ( 12 ) has been synthesized from the corresponding carboxylate 15 by a reduction (LiAlH₄) and dehydrogenation (MnO₂) sequence (see Scheme 2). The Swern oxidation of the intermediate 2-(hydroxymethyl)azulene 16 yielded only 1,3-dichloroazulene derivatives (cf. Scheme 2). The Wittig reaction of 12 with 4a and 4b in the presence of EtONa/EtOH in toluene yielded the expected 2-styryl derivatives 19a and 19b , respectively (see Scheme 3). Again, the yield of 19b was reduced by a competing alkylation reaction of 19b with 4b which led to the formation of the 1-benzylated product 20 (see Scheme 3). The ‘anil synthesis’ of guaiazulene ( 21 ) and the 4-R-benzanils 22 (R=H, MeO, Cl, Me₂N) proceeded smoothyl under standard conditions (powered KOH in DMF) to yield the corresponding 4-[(E)-styryl]azulene derivatives 23 (see Table 4). In minor amounts, bis(azulen-4-yl) compounds of type 24 and 25 were also formed (see Table 4). The ‘anil reaction’ of 21 and 4-NO₂C₆H₄CH=NC₆H₅ ( 22e ) in DMF yielded no corresponding styrylazulene derivative 23e . Instead, (E)-1,2-bis(7-isopropyl-1-methylazulen-4-yl)ethene ( 27 ) was formed (see Scheme 4). The reaction of 4,6,8-trimethylazulene ( 10 ) and benzanil ( 22a ) in the presence of KOH in DMF yielded the benzanil adducts 28 to 31 (cf. Scheme 5). Their direct base-catalyzed transformation into the corresponding styryl-substituted azulenes could not be realized (cf. Scheme 6). However, the transformation succeeded smoothly with KOH in boiling EtOH after N-methylation (cf. Scheme 6).     

N-monoaryldithiocarbamate cobalt(III) complexes(1)

Summary Diamagnetic cobalt(III) complexes of the type (RHNCS₂)₃Co [R = Ph, XC₆H₄ (X=p-Me,p-OMe,p-Cl,p-Br andp-I) and 2,4-Me₂C₆H₃] have been synthesised by reaction of the corresponding dithiocarbamate ammonium salts and hexaaquocobalt(II) chloride. Ligand field parameters calculated from visible spectral data indicate strong covalent character for the Co-S bond. The i.r. spectral data reveal that the CN bond in these dithiocarbamates has less double bond character compared to the corresponding dialkyldithiocarbamates.     

Reactions of <Emphasis Type="Italic">N</Emphasis>-and <Emphasis Type="Italic">C</Emphasis>-Alkenylanilines: VII. Synthesis of Indole Heterocycles from Products of Reaction between <Emphasis Type="Italic">N</Emphasis>-Mesyl-2-(1-alken-1-yl)anilines and Halogens

N-Mesyl-2-(1-methyl-1-butenyl)-6-methylaniline reacted with Br₂ to afford N-mesyl-2-(3-bromo-1-penten-2-yl)aniline that under treatment with NH₃ or amines underwent cyclization into N-mesyl-7-methyl-3-methylene-2-ethylindoline. The reaction of N-mesyl-2-(1-methyl-1-buten-1-yl)-4-methyl- and 2-(1-methyl-1-buten-1-yl)aniline with Br₂ gave rise to the corresponding N-mesyl-2-(2-bromo-1-methyl-1-buten-1-yl)anilines. Under the similar conditions N-tosyl-2-(1-cyclohexen-1-yl)aniline was converted into N-tosyl-2-(6-bromo-1-cyclohexen-1-yl)aniline that under treatment with NH₃ furnished N-tosyl-1,2,3,9a-tetrahydrocarbazole. The reaction of N-mesyl-1,2,3,9a-tetrahydrocarbazole with CuBr₂ in MeOH afforded N-mesyl-4-methoxy-1,2,3,4-tetrahydrocarbazole. N-Mesyl-6-methyl-2-(1-cyclopenten-1-yl)aniline in reaction with Br₂ in the presence of NaHCO₃ was oxidized into the corresponding cyclopentenone, and with NBS it gave N-mesyl-2-(2-bromo-1-cyclopenten-1-yl)aniline.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 730–737.Original Russian Text Copyright © 2005 by Gataullin, Sotnikov, Spirikhin, Abdrakhmanov.     

Star-shaped polymers by living cationic polymerization. VII. Amphiphilic graft polymers of vinyl ethers with hydroxyl groups: Synthesis and host–guest interaction

Amphiphilic graft polymers of vinyl ethers (VEs) ( 6 ) where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(alkyl vinyl ether) segment were prepared on the basis of living cationic polymerization, and their properties and functions were compared with the corresponding amphiphilic star-shaped polymers. In toluene at ?15°C, the HI/ZnI₂-initiated living block polymer 2 of an ester-containing VE (CH₂? CHOCH₂CH₂OCOCH₃) and isobutyl VE (IBVE) was terminated with the diethyl 2-(vinyloxy)ethylmalonate anion [ 3 ; ^ΦC(COOEt)₂CH₂CH₂OCH ? CH₂] ( 2/3 = 1/2 mole ratio) to give a macromonomer ( 4 ), H[CH₂CH(OCH₂CH₂OCOCH₃)] _m-[CH₂CH(OiBu)]_n? C(COOEt)₂CH₂CH₂OCH ? CH₂ (m = 5, n = 15; M?_n = 2600, M?_w/M?_n = 1.13, 1.10 vinyl groups/chain). Subsequently, 4 was homopolymerized with HI/ZnI₂ in toluene at ?15°C. In 3 h, 85% of 4 was consumed and a graft polymer ( 5 ) was obtained [M?_w = 15000, DP_n (for 4 ) = 6]. The apparent M?_w (10,900) of 5 by size-exclusion chromatography (SEC) is smaller than that by light scattering as well as that (18,300) by SEC of the corresponding linear polymer with the almost same molecular weight, indicating the formation of a multi-branched structure. Hydrolysis of the pendant esters in 5 gave the amphiphilic graft polymer 6 where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(IBVE) segment. The graft polymer 6 was found to interact specifically with small organic molecules (guests) with polar functional groups, and 6 differed in solubility and host-guest interaction from the corresponding star-shaped polymer. © 1993 John Wiley & Sons, Inc.     

Conformational Equilibria and Large‐Amplitude Motions in Dimers of Carboxylic Acids: Rotational Spectrum of Acetic Acid–Difluoroacetic Acid

We report the rotational spectra of two conformers of the acetic acid–difluoroacetic acid adduct (CH₃COOH–CHF₂COOH) and supply information on its internal dynamics. The two conformers differ from each other, depending on the trans or gauche orientation of the terminal ?CHF₂ group. Both conformers display splittings of the rotational transitions, due to the internal rotation of the methyl group of acetic acid. The corresponding barriers are determined to be V₃(trans)=99.8(3) and V₃(gauche)=90.5(9) cm^?1 (where V₃ is the methyl rotation barrier height). The gauche form displays a further doubling of the rotational transitions, due to the tunneling motion of the ?CHF₂ group between its two equivalent conformations. The corresponding B₂ barrier is estimated to be 108(2) cm^?1. The increase in the distance between the two monomers upon OH→OD deuteration (the Ubbelohde effect) is determined.     

1-Amino-2-phthalimido-diazen-1-oxide: Bildung,Eigenschaften und Fragmentierungen in Imido- und Amino-nitrene

1-Amino-2-phthalimido-diazene-1-oxides: Formation, Properties and Fragmentation Reactions into Imido- and Amino-nitrenes¹) Oxidatively generated phthalimido-nitrene ( 1 ) reacts with the nitrosoamines 2a-d (see Scheme 1) to give the corresponding (Z)-1-amino-2-phthalimido-diazene-1-oxides 3a-d in good yields. With the O-nitroso compound 2e , no addition of the nitrene 1 took place. The constitution the adducts 3 (R = NR′₂) is deduced from their spectroscopic properties (UV., IR., ¹H-NMR. and MS.) as compared to those of (Z)-1-aryl- and (Z)-1-alkyl-2-phthalimido-diazene-1-oxides 3 (R = aryl and alkyl, resp.). The (Z)-configuration of 3 (R = NR′₂) follows from an X-ray analysis which is reported separately. Compounds 3 (R = NR′₂) are cleaved photolytically as well as by acid to the corresponding nitrosoamines 2 (R = NR′₂) and the nitrene 1 , which could be trapped by cyclohexene to give 40% of 7-phthalimido-7-azabicyclo [4.1.0]heptane ( 8 ) and by dimethylsulfoxide to yield 96% of S, S-dimethyl-N-phthalimido-sulfoximide ( 13 ). Nucleophilic attack leads to fragmentation of 3 (R = NR′₂) into derivatives of phthalic acid and degradation products of intermediate aminonitrenes 24 corresponding to the respective nitrosoamines 2 (R = NR′₂) with loss of oxygen. A general rationalization for the formation of 24 includes as a key step of N- to C-migration of the O-atom (see Scheme 6). The final fate of 24 is depending on the type of the nucleophile used. Thus, hydrazinolysis of 3b and of 3c generates besides N, N′-phthaloylhydrazine ( 15 ), morpholine ( 14 ) from 3b and 1, 3-dihydroisoindole ( 16 ) together with 6′-methylidene-1, 2, 3, 4-tetrahydronaphthalene-2-spiro-1′-cyclohexa-2′, 4′-diene ( 17 ) from 3c (see Scheme 5). Treatment of 3b and of 3c with sodium methylate leads in both reactions to monomethyl phthalate ( 33 ) and, with 3b , to 1, 2-dimorpholinodiazene ( 31 ) and, with 3c , to 17 (see Scheme 7). Finally, the reaction of 3b with diethylamine generates N, N-diethylphthalamic acid ( 36 ), morpholine ( 14 ), 1,1,4,4-tetraethyl-2-tetrazene( 34 ) and l,l-diethyl-4,4-(3-oxapentamethylene)-2-tetrazene ( 35 ) (see Scheme 8).     

Transition metal complexes with bidentate ligands spanning trans-positions. IV. Preparation and properties of some rhodium and iridium complexes of 2,11-bis(diphenylphosphinomethyl)benzo [c]phenanthrene

The bidentate phosphine 2,11-bis(diphenylphosphinomethyl)benzo [c]phenanthrene ( 1 ) has been used to prepare the mononuclear, square planar complexes trans-[MX(CO)( 1 )] and trans-[M(CO)(CH₃CN)( 1 )][BF₄] (M = Rh, Ir; X = Cl, Br, I, NCS). It is found that the tendency of these complexes to form adducts with CO, O₂ and SO₂ is significantly lower than that of the corresponding Ph₃P complexes. The oxidative-addition reactions of complexes trans-[IrX (CO) ( 1 )] with hydrogen halides give the six-coordinate species [IrHX₂(CO) ( 1 )]. The complexes [IrH₂I (CO) ( 1 )] and [IrH₂L (CO) ( 1 )] [BF₄] (L = CO and CH₃CN) have been obtained from hydrogen and the corresponding substrates. The model compounds trans-[MCl (CO) (Ph₂PCH₂Ph)₂] (M = Rh, Ir), trans-[Ir (CO) (CH₃CN) (Ph₂PCH₂Ph)₂] [BF₄], [IrHCl₂(CO)(Ph₂PCH₂Ph)₂] and [IrH₂(CO)₂(Ph₂PCH₂Ph)₂] [BF₄] have been prepared and their special parameters are compared with those of the corresponding complexes of ligand 1 . The influence of the static requirements of this ligand on the chemistry of its rhodium and iridium complexes is discussed.     

Isolable Anionic,Neutral and Cationic Radicals from Reactions of N,N′-Dimesityldiamidocarbene and Lewis Acids

B(C₆F₅)₃ undergoes nucleophilic attack by N,N′-dimesityldiamidocarbene (DAC) with fluoride transfer to the boron center, resulting in a new zwitterion ( 1 ). This B−F fluoride can be replaced or abstracted to give the corresponding hydride ( 2 ) or triflate ( 3 ) derivatives or the corresponding cation ( 4 ). These species are reduced with KC₈ or Cp₂Co to give isolable anionic and neutral radicals ( 5 – 8 ). Similarly, the [Ph₃C] cation undergoes nucleophilic attack by DAC resulting in the spontaneous formation of the radical cation ( 9 ).     

Reaction of Hydroxymethyl- and Alkyl-Substituted Azulenes with Manganese Dioxide

It is shown that the 2-(hydroxymethyl)-1-methylazulenes 6 are being oxidized by activated MnO₂ in CH₂Cl₂ at room temperature to the corresponding azulene-1,2-dicarbaldehydes 7 (Scheme 2). Extension of the MnO₂ oxidation reaction to 1-methyl- and/or 3-methyl-substituted azulenes led to the formation of the corresponding azulene-1-carbaldehydes in excellent yields (Scheme 3). The reaction of unsymmetrically substituted 1,3-dimethyl-azulenes (cf. 15 in Scheme 4) with MnO₂ shows only little chemoselectivity. However, the observed ratio of the formed constitutionally isometric azulene-1-carbaldehydes is in agreement with the size of the orbital coefficients in the HOMO of the azulenes. The reaction of guaiazulene ( 18 ) with MnO₂ in dioxane/H₂O at room temperature gave mainly the expected carbaldehyde 19 . However, it was accompanied by the azulene-diones 20 and 21 (Scheme 5). The precursor of the demethylated compound 20 is the carbaldehyde 19 . Similarly, the MnO₂ reaction of 7-isopropyl-4-methyalazulene ( 22 ) as well as of 4,6,8-trimethylazulene ( 24 ) led to the formation of a mixture of the corresponding azulene-1,5-diones and azulene-1,7-diones 20 / 23 and 25 / 26 , respectively, in decent yields (Schemes 6 and 7). No MnO₂ reaction was observed with 5,7-dimethylazulene.     

Radical Arylation Reactions of 4, 6, 8-Trimethylazulene

The synthesis of 1- and 2-aryl-substituted (aryl = Ph, 4-NO₂? C₆H₄, and 4-MeO? C₆H₄) 4, 6, 8-trimethylazulenes ( 4 and 3 , respectively) in moderate yields by direct arylation of 4, 6, 8-trimethylazulene ( 8 ) with the corresponding arylhydrazines 13 in the presence of Cu^IIions in pyridine (see Scheme 4) as well as with 4-MeO? C₆H₄Pb(OAc)₃ ( 16 ) in CF₃COOH (see Scheme 5) is described. With 13 , also small amounts of 1, 2- and 1, 3-diarylated azulenes (see 14 and 15 , respectively, in Scheme 4) are formed. The 4-methoxyphenylation of 8 with 16 yielded also the 1, 1′-biazulene 17 in minor amounts (see Scheme 5). 4, 6, 8-Trimethyl-2-phenylazulene ( 3a ) was also obtained as the sole product in moderate yields by the reaction of sodium phenylclopentadienide ( 1a ) with 2, 4, 6-trimethylpyrylium tetrafluoroborate ( 2 ) in THF (Scheme 1). The attempted phenylation of 8 as well as of azulene ( 9 ) itself with N-nitroso-N-phenylacetamide ( 10 ) led only to the formation of the corresponding 1-(phenylazo)-substituted azulenes 12 and 11 , respectively (Scheme 3).     

High-Yield Syntheses of Sodium,Potassium, and Thallium Hydrotris[3,5-bis(trifluoromethyl)pyrazolyl]borates and the X-ray crystal structure of {hydrotris[3,5-bis(trifluoromethyl)pyrazolyl]borato} thallium(I)

An improved synthesis of 3,5-bis(trifluoromethyl)pyrazole ( 1 ) is described. This compound was used for the high-yield syntheses of the tris(pyrazoly1)borates Nd[HB(3,5-(CF₃),-pz)₃] ( 2a ) and the corresponding potassium salt, 2b , starting from 1 and NaBH₄ and KBH₄, respectively. A convenient route to the corresponding thallium(I) salt, 2c , using thallium(I) acetate and either 2a or 2b in CHCI₃, is also described. The sodium ( 3a ), potassium ( 3b ), and thallium ( 3c ) salts of bis(pyrazolyl)borate [H₂B(3,5-(CF₃)₂-pz)₂]^? were also prepared. The above pyrazolylborates were characterized by ¹H-, ¹³C-, ¹⁹F-, and ¹¹B-NMR spectroscopy. The X-ray crystal structure of the thallium derivative 2c was determined. The compound crystallizes in the monoclinic space group P2₁/m with a = 8.248(9) Å, b = 15.034(12) Å c = 9.243(8) Å, β = 100.10(7)°, Z = 2. The Tl-atom adopts a pyramidal geometry with respect to the three N-atoms. However, two TI–N distances (2.725(7) Å) are longer than the third (2.675(10) Å).     

Synthesis and Copper(I) Complexes of a Series of 9- to 13-Membered N3 Macrocycles

Eight cyclic triamines with ring sizes between 9 and 13 were synthesized by the p-toluenesulfonate method. The open-chain triamines bis(2-aminoethyl)amine (dien) and bis(3-aminopropyl)amine (diprop) were used as starting materials. In some cases, the corresponding dimeric cyclic hexaamines have been isolated and characterized as major by-products. The complexation of Cu(I) by the triamines has been studied potentiometrically in CH₃CN/H₂O. All ligands L form ternary complexes [Cu(CH₃CN)L]⁺. The corresponding association constants vary between 10¹¹ and 10⁷, decreasing with increasing ring size. In addition, complexes [Cu(CH₃CN)_yLH]²⁺, y = 1 or 2, are found as less important species with maximum concentrations of 7 to 50%.