Malonate Anion Research Articles

New types of the flexible self-assembled metal–organic coordination polymers constructed by aliphatic dicarboxylates and rigid bidentate nitrogen ligands

The reaction of metal ions, flexible aliphatic dicarboxylates and rigid bidentate linear ligands under mild conditions in water afford four novel metal-organic coordination polymers, [Cd(mu-mal)(mu-pyz)(0.5)(H(2)O)](n) 1 (mal = malonate dianion, pyz = pyrazine), [Cd(2)(mu-suc)(2)(mu-pyz)(H(2)O)(2)](n) 2 (suc = succinate dianion), and ([M(mu-bipy)(H(2)O)4][suc].4H(2)O)(n)(M = Co, 3, M = Zn, 4, bipy = 4,4'-bipyridine). The molecular structures of 1-4 have been established by single-crystal X-ray crystallography. 1 is a 3D network being composed of layers of octahedrally coordinated Cd atoms bridged by malonate anions in syn-anti configurations within the layers and pyz molecules between layers. Unlike that in 1, each Cd atom in 2 displays uncommon pentagonal-bipyramidal geometry to form 2D infinite grid sheets with square grid dimensions of ca. 7.936 x 7.936 [Angstrom]. Both 3 and 4 exhibit 1D linear -M-bipy-M-bipy- chain polymers, and these chains were packed as ...ABCABC... layered structures. The bridging succinate ligands in 2 adopt the syn-anti mode with a torsion angle of 60.8(7) degrees, while the solvated succinate ligands in 3 and 4 adopt the anti-anti mode with a torsion angle of 180.0 degrees. To our knowledge, compound 2 represents the first example of flexible self-assembled succinate-pyrazine mixed bridging ligand coordination network. 3 and 4 are the first two cases of succinate-bipy polymers with non-coordinated succinate. The magnetic behavior for 3 was studied in the temperature range of 5-300 K. The result indicates the occurrence of a weak antiferromagnetic coupling between the cobalt(II) ions.

Combining phosphinidene units with malonate anion: Synthesis of highly functional phosphine complexes

AbstractMalonate anion traps the [RP‐W(CO)5] bridge of 7‐phosphanorbornadiene complexes 1–3 to give functional secondary phosphine complexes [RP(H)‐CH(CO2Et)2]W(CO)5 (7–9). Metalation of these complexes by NaH in THF occurs at the malonic CH group, but the alkylation of the resulting carbanions preferentially takes place at phosphorus. When R stands for β‐chloroethyl, the corresponding carbanion cyclizes to give the functional phosphirane complex 11. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:258–262, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20014

Solid-state versus solution preparation of two crystal forms of [HN(CH2CH2)3NH][OOC(CH2)COOH]2. Polymorphs or hydrogen bond isomers?

The reaction of [N(CH2CH2)3N] with malonic acid [HOOC(CH2)COOH] in the molar 1:2 ratio yields two different crystal forms of the salt [HN(CH2CH2)3NH][OOC(CH2)COOH]2 depending on the preparation technique and crystallization speed: form I, containing malonate anions with intramolecular hydrogen bonds, is obtained by solid-state co-grinding or by rapid crystallization, whereas form II containing intermolecular hydrogen bonds is obtained by slow crystallization. Form I and II do not interconvert, and form I undergoes an order-disorder phase transition on cooling.

Supramolecular aggregates between carboxylate anions and an octaaza macrocyclic receptor.

The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recognition of aromatic and aliphatic carboxylate substrates. The receptor-substrate binding behaviour of (H6Me2[28]py2N6)6+ with an aliphatic (-O2C(CH2)nCO2-, n=0 to 4) and an aromatic (phthalate, isophthalate, terephthalate, 4,4'-dibenzoate, benzoate, 3- and 4-nitrobenzoate) series of carboxylate anions was evaluated by 1H NMR spectroscopy (carried out in DMSO-d6 at 300 K). Two association constants were found for most of the studied cases, except for 3- and 4-nitrobenzoate for which only K1 was determined. For oxalate, malonate, benzoate and dibenzoate anions only the beta2 constants could be obtained. The values of the first association constant cover a range from 2.86 to 3.69 (log units), and the second stepwise constant from 2.15 to 2.89 (also in log units). No special selectivity was found but the highest values were determined for adipate and the lowest for the monoprotic 3- and 4-nitrobenzoates. Single crystal X-ray structures of H6Me2[28]py2N6 6+ with terephthalate, 1, and 4,4'-dibenzoate (2) were determined showing supramolecular entities with general formula (H6Me2[28]py2N6).(substrate)2(PF6)2.4H2O. These anions are the building blocks of an extensive 3-D network of hydrogen bonds.

Synthesis, crystal structure and magnetic properties of two-dimensional malonato-bridged cobalt(ii) and nickel(ii) compounds

Two isostructural malonato-bridged complexes of formula {[M(H2O)2][M(mal)2(H2O)2]}n [M = Co(II) (1), Ni(II) (2); H2mal = malonic acid] have been synthesised and characterized by X-ray diffraction. Their structure consists of corrugated layers of trans-diaquabismalonatemetalate(II) and trans-diaquametal(II) units bridged by carboxylate–malonate groups in the anti–syn conformation. Two crystallographycally independent metal atoms occur in 1 and 2. The malonate anion acts simultaneously as a bidentate and bis-monodentate ligand. Variable-temperature (1.9–295 K) magnetic susceptibility measurements indicate the occurrence of weak antiferro- (1) and ferromagnetic (2) interactions between the cobalt(II) (1) and nickel(II) ions (2) through the anti–syn caboxylate–malonate bridge. A brief discussion on the structural diversity and crystal engineering possibilities of the malonate complexes with divalent first-row transition metal ions other than copper(II) is carried out.

Solution equilibria leading to the formation of metal–metal bonds in partially oxidized bisoxalatoplatinate(II) systems

The reaction between [Pt II(Ox) 2] 2− and an appropriate oxidant resulted in the formation of the dimeric unbridged platinum complex [{Pt III(Ox) 2 } 2] 2− where (Ox) is oxalate. This complex was moderately stable under ambient conditions and was studied via a variety of NMR and spectrophotometric techniques. Reaction of the [{Pt III(Ox) 2} 2] 2− complex with [Pt II(Ox) 2] 2− in the presence of H + lead to the formation of a series of longer platinum oligomers with non-integral oxidation states, culminating in the formation of partially oxidized platinum polymers of general formula [{Pt(Ox) 2} n ] n− . The concentration of H + was an important factor leading to higher oligomers and the approximate number of protons associated with each oligomer was determined. The analogous [{Pt III(Mal) 2} 2] 2− complex, where (Mal) is the malonate anion, was also synthesized and studied but was shown to be significantly less stable.

2H-quadrupolar coupling-based analysis of stereochemical and regiochemical memory in the Pd-catalysed allylic alkylation of iso-cinnamyl type substrates employing the chiral monophosphine ligands ‘MOP’ and ‘MAP’

The reaction of iso-cinnamyl acetate with NaC(Me)(CO 2Me) 2, catalysed by Pd–‘MOP’ (MOP=2-methoxy-2′-diphenylphosphino-1,1′-binaphthalene) is known to proceed with a regiochemical memory effect that results in the predominant generation of the branched alkylation product. The analogous reaction employing ‘MAP’ as ligand (MAP=2- N, N-dimethylamino-2′-diphenylphosphino-1,1′-binaphthalene) proceeds with ‘normal’ regioselectivity to generate predominantly the linear isomer of product. A 2H-NMR based analysis, employing quadrupolar coupling in a chiral liquid crystal matrix, has been developed to facilitate the simultaneous study of the regiochemical and stereochemical outcome of the reaction of both enantiomers of iso-cinnamyl ester substrates in 2H-labelled but racemic samples. The analysis allows the comparison of relative rates of two competing isomerisation processes occurring in the π-allyl intermediates in the Pd-catalysed reaction, one of which facilitates asymmetric induction, the other resulting in loss of regiochemical memory. It is demonstrated that the two processes are partially coupled and that this then limits the attainment of high global enantiomeric excess in the branched product to reactions that proceed with low regiochemical retention. A key factor for the observation of high regiochemical memory is found to be the nucleophilicity of the malonate anion and the electrophilicity of the Pd–π-allyl intermediate with reduction in the reactivity of either partner resulting in the onset of substantial loss of memory.

The Polar Effect on the Regiochemistry of Nucleophilic Substitution of Trifluoromethylated π‐Allylpalladium Complex.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Palladium-catalyzed benzylic-like nucleophilic substitution of benzofuran-, benzothiophene- and indole-based substrates by dimethyl malonate anion

The palladium-catalyzed benzylic-like nucleophilic substitution of acetates derived from benzofuran, benzothiophene and indole was investigated. The asymmetric substitution on racemic 1-(2-benzofuryl)ethyl acetate gave disappointing results, but the substitution product was obtained in 98% ee from ( S)-1-(2-benzofuryl)ethyl acetate with overall retention of configuration.

Polymeric aqua(benzimidazole-κN)(μ-malonato)cobalt(II)

The crystal structure of the title compound, [Co(C3H2O4)(C7H6N2)(H2O)]n, consists of two-dimensional polymeric CoII complex layers. The octahedral coordination around a CoII atom is composed of a chelate malonate, two monodentate malonate anions from the adjacent asymmetric unit, a bez­imidazole ligand and a coordinated water molecule. Each malonate dianion links three CoII atoms related by an n-glide plane to form polymeric layers in the (010) plane. π–π stacking of the benz­imidazole ligands occurs between adjacent polymeric layers, the separation between parallel benz­imidazole rings being 3.42 (2) A.

Fluoroalkylation of Porphyrins: Synthesis and Reactions of β‐Fluoroalkyltetraarylporphyrins.

Treatment of 5,10,15,20-tetraarylporphyrins (1) with perfluoroalkyl iodides (2) in the presence of Na2S2O4/NaHCO3 in DMSO−CH2Cl2 at 30−40 °C for several hours gives the corresponding 2-perfluoroalkylporphyrins (3). Nucleophilic attack on 3 with dimethyl malonate, diethyl malonate, malonitrile, or cyano acetate (Nu) anion results in the formation of (E)-3-Nu-2-perfuoroalkyl(methylenyl)chlorins. Electrophilic substitution on 3 with NBS or NO2 affords regioselectively the corresponding 12(or 13)-bromo- and 12,13-dibromo- or nitroporphyrins.

The polar effect on the regiochemistry of nucleophilic substitution of trifluoromethylated π-allylpalladium complex

Allylic nucleophilic substitution of trifluoromethyl-group substituted cinnamyl carbonate with diethyl malonate anion in the presence of palladium complex catalyst gave regio- and stereoselectively the S N2′ product. The regiochemistry caused by the polar effect of trifluoromethyl group was opposite to the methylated cinnamyl substrate in a similar steric environment. The sterically more hindered mesityl and tert-butyl substrates than phenyl derivative also gave the products reacted at the more hindered sites. Although o-substituted substrates expecting intramolecular coordination to affect regiochemistry were examined, no alternative regioisomers were detected.

Fluoroalkylation of porphyrins: synthesis and reactions of beta-fluoroalkyltetraarylporphyrins.

Treatment of 5,10,15,20-tetraarylporphyrins (1) with perfluoroalkyl iodides (2) in the presence of Na(2)S(2)O(4)/NaHCO(3) in DMSO-CH(2)Cl(2) at 30-40 degrees C for several hours gives the corresponding 2-perfluoroalkylporphyrins (3). Nucleophilic attack on 3 with dimethyl malonate, diethyl malonate, malonitrile, or cyano acetate (Nu) anion results in the formation of (E)-3-Nu-2-perfuoroalkyl(methylenyl)chlorins. Electrophilic substitution on 3 with NBS or NO(2) affords regioselectively the corresponding 12(or 13)-bromo- and 12,13-dibromo- or nitroporphyrins.

Syntheses of two new 1D and 3D networks of Cu(II) and Co(II) using malonate and urotropine as bridging ligands: crystal structures and magnetic studies.

Two new metal-organic based polymeric complexes, [Cu(4)(O(2)CCH(2)CO(2))(4)(L)].7H(2)O (1) and [Co(2)(O(2)CCH(2)CO(2))(2)(L)].2H(2)O (2) [L = hexamethylenetetramine (urotropine)], have been synthesized and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 is a 1D coordination polymer comprising a carboxylato bridged Cu(4) moiety linked by a tetradentate bridging urotropine. Complex 2 is a 3D coordination polymer made of pseudo-two-dimensional layers of Co(II) ions linked by malonate anions in syn-anti conformation which are bridged by bidentate urotropine in trans fashion. Complex 1 crystallizes in the orthorhombic system, space group Pmmn, with a = 14.80(2) A, b = 14.54(2) A, c = 7.325(10) A, beta = 90 degrees, and Z = 4. Complex 2 crystallizes in the orthorhombic system, space group Imm2, a = 7.584(11) A, b = 15.80(2) A, c = 6.939(13) A, beta = 90.10 degrees (1), and Z = 4. Variable temperature (300-2 K) magnetic behavior reveals the existence of ferro- and antiferromagnetic interactions in 1 and only antiferromagnetic interactions in 2. The best fitted parameters for complex 1 are J = 13.5 cm(-)(1), J' = -18.1 cm(-)(1), and g = 2.14 considering only intra-Cu(4) interactions through carboxylate and urotropine pathways. In case of complex 2, the fit of the magnetic data considering intralayer interaction through carboxylate pathway as well as interlayer interaction via urotropine pathway gave no satisfactory result at this moment using any model known due to considerable orbital contribution of Co(II) ions to the magnetic moment and its complicated structure. Assuming isolated Co(II) ions (without any coupling, J = 0) the shape of the chi(M)T curve fits well with experimental data except at very low temperatures.

4‐Ferrocenyl‐1,3‐oxazoline Derivatives as Ligands for Catalytic Asymmetric Allylation Reactions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Asymmetric palladium-catalyzed nucleophilic substitution of 1-(2-naphthyl)ethyl acetate by dimethyl malonate anion

The asymmetric palladium-catalyzed nucleophilic substitution of 1-(2-naphthyl)ethyl acetate (1) by dimethyl malonate anion was realized and led to dimethyl 2-[1-(2-naphthyl)ethyl]propanedioate (2) with up to 74% ee. The analysis of the course of the reaction gave some information on the behaviour of the intermediate complexes.

Stereocontrolled total synthesis of (+)-vinblastine

Abstract Stereocontrolled total synthesis of (+)-vinblastine (1) has been achieved using a novel radical-mediated indole synthesis developed in our laboratories. The isothiocyanate 18, prepared readily from quinoline 17, underwent a facile addition of the malonate anion to give 19. The o-alkenylthioanilide 19 was then converted to indole 20 by radical cyclization and protection. (−)-Vindoline (2) was prepared from this key intermediate 20 in a highly efficient manner. The indole core of the 11-membered intermediate 3 was constructed similarly from quinoline. The critical coupling reaction between 2 and the chloroindolenine derived from 3 proceeded with complete control of stereochemistry to give the desired product 66 in 97 % yield, which could be successfully converted to (+)-vinblastine (1).

Generation of reactivity from typically stable ligands: CbondC bond-forming reductive elimination from aryl palladium(II) complexes of malonate anions.

Generation of reactivity from typically stable ligands: CbondC bond-forming reductive elimination from aryl palladium(II) complexes of malonate anions.

Generation of Reactivity from Typically Stable Ligands: CC Bond‐Forming Reductive Elimination from Aryl Palladium( II ) Complexes of Malonate Anions

Generation of Reactivity from Typically Stable Ligands: CC Bond‐Forming Reductive Elimination from Aryl Palladium( <scp>II</scp> ) Complexes of Malonate Anions

4-Ferrocenyl-1,3-oxazoline derivatives as ligands for catalytic asymmetric allylation reactions

Bis(oxazolines) and 2-(2-phosphinoaryl)oxazolines derived from highly enantiopure 2-amino-2-ferrocenylethanol have been tested as ligands in the asymmetric Pd(0)-catalysed allylic alkylation reaction. Essentially complete enantioselectivity (99.8:0.2 er) has been achieved in the nucleophilic substitution of 1,3-diphenyl-2-propenyl acetate by dimethyl malonate anion. The absolute configuration of the ligands has been unambiguously established by chiroptical methods.