“Umgepolte” 1.3-diaza-fulvene

6-Substituted 2.4-diamino-1.3-diazafulvenes with inverse fulvene polarity are readily available from 2.4.5-tris-(diethylamino)-4-ethoxy-4H-imidazole and active methylene compounds.     

Dynamic [2]catenanes based on a hydrogen bonding-mediated bis-zinc porphyrin foldamer tweezer: a case study

This paper describes the self-assembly of a new class of three-component dynamic [2]catenanes, which are driven or stabilized by intramolecular hydrogen bonding, coordination, and electrostatic interaction. One of the component molecules 2, consisting of an aromatic oligoamide spacer and two peripheral zinc porphyrin units, was designed to adopt a folded preorganized conformation, which is stabilized by consecutive intramolecular three-centered hydrogen bonds. Component molecule 3 is a linear secondary ammonium bearing two peripheral pyridine units, which was designed to form a 1:1 complex with 24-crown-8 (5). The 1H NMR and UV-vis experiments in CDCl3-CD3CN (4:1 v/v) revealed that, due to the preorganized U-shaped feature, 2 could efficiently bind 3 through the cooperative zinc-pyridine coordination to generate highly stable 1:1 complex 2.3. Adding 5 to the 1:1 solution of 2 and 3 led to the formation of dynamic three-component [2]catenane 2.3.5 as a result of the threading of 3 through 5. 1H NMR studies indicated that in the 1:1:1 solution (3 mM) [2]catenane 2.3.5 was generated in 55% yield at 25 degrees C. The yield was increased with the reduction of the temperature and [2]catenane could be produced quantitatively in a 1:1:2 solution ([2]=3 mM) at -13 degrees C. Replacing 3 with 1,2-bis(4,4'-bipyridinium)ethane (4) in the three-component solution could also give rise to similar dynamic [2]catenane 2.4.5 albeit in slightly lower yield.     

Syntheses, structures, and luminescent and magnetic properties of novel three-dimensional lanthanide complexes with 1,3,5-benzenetriacetate

Five novel lanthanide complexes with the formulas [Nd(bta)(H2O)2.4.35H2O]n(1), [Sm(bta)(H2O)2.4.5H2O]n (2), [Eu(bta)(H2O).1.48H2O]n (3), [Tb(bta)(H2O).1.31H2O]n (4), and [Yb(bta)(H2O).H2O]n (5) (H3bta = 1,3,5-benzenetriacetic acid) have been prepared by using the corresponding lanthanide salt and H3bta. The results of an X-ray crystallographic analysis revealed that all the complexes have three-dimensional channel-like structures, in which the bta3- ligands adopt different coordination modes: monodentate and mu2-eta2:eta1-bridging coordination modes in 1, 2, and 5 and mu2-eta1:eta1-bridging and mu2-eta2:eta1-bridging coordination modes in 3 and 4, respectively. Complexes 1 and 2, as well as 3 and 4, are isostructural, respectively, in which all the Ln(III) (Ln = Nd, Sm, Eu, and Tb) atoms are nine-coordinated, while the Yb(III) atoms in complex 5 are eight-coordinated. Both complexes 3 and 4 showed strong luminescence upon excitation, and their luminescence decay curves fit well with single exponential decays of which the lifetime is 0.45 ms for 3 and 1.0 ms for 4. The magnetic properties of the complexes were investigated in the temperature range of 1.8-300 K.     

Pentanuclear and heptanuclear helicates by self-assembly of d10 metal ions and a rigid aromatic bis-bidentate chelator

The self-assembly of Zn(II) and Cd(II) ions with a bis-bidentate ligand 3,5-bis(benzimidazol-2-yl)pyrazole (H 3L) was studied by Electrospray ionization mass spectrometry, (1)H NMR measurements, and single-crystal X-ray diffraction analyses. Reaction of Zn(ClO 4) 2.6H 2O and Cd(ClO 4) 2.6H 2O with H 3L in DMF gave two pentanuclear complexes [(Zn 5(mu 3-O)(H 2L) 6)(ClO 4) 2.DMF.9.5H 2O ( 1) and [Cd 5(mu 3-O)(H 2L) 6](ClO 4)(OH).4.75DMF.0.25EtOH.10.5H 2O ( 2), in which the trigonal-bipyramidal core structures are bridged by mu 3-oxo and pyrazolate rings of the monodeprotonated H 2L. When Na 3PO 4.12H 2O was used in the reaction system of CdBr 2.4H 2O and H 3L, [Cd 5(mu 3-O)(H 2L) 6]Br 2.4.5DMF.6.5H 2O ( 3) and [Cd 7(mu 6-PO 4)(mu-Br) 3(H 2L) 6](HPO 4).DMF.10H 2O ( 4) were isolated. 3 displays the same core structure as that of 2, whereas 4 exhibits a turbinate, heptanuclear core which is bridged by a mu 6-PO 4, three mu-Br, and three pyrazolate rings. All of the pentanuclear and heptanuclear cores are surrounded by three pairs of bis-bidentate H 2L (-) ligands with offset pi-pi stacking, showing propeller-like molecular structures and triple-stand helicates. Electrospray ionization mass spectrometry studies and (1)H NMR measurements demonstrate that the pentanuclear complexes have different stability in the solution, depending on the metal ions and the counteranions. Furthermore, both 1 and 2 emit blue fluorescence with nanosecond luminescent lifetimes in DMF at room temperature.     

Über die Synthese von 4-Amino-2H-imidazolen aus Imidazolin-Δ3-thionen-(5)

Zusammenfassung 2,4,5-substituierte 4-Alkylamino-2H-imidazole entstehen mit guten Ausbeuten aus 2-Methyl-2,4-diaryl-imidazolin-³-thionen-(5) durch Umsetzung mit prim. bzw. sek. aliphatischen oder heterocyclischen Aminen in Benzol bei Rückflußtemperatur.

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2.4.5-substituted 4-alkylamino-2H-imidazoles are formed in good yields by the reaction of 2-methyl-2.4-diaryl-³-imidazoline-5-thiones with prim. or sec. aliphatic or heterocyclic amines in boiling benzene.

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55. Mitt.:F. Asinger, E.-Chr. Witte undW. Schäfer, Ann. Chem., im Druck.

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Teil der DissertationG. Kriebel, Techn. Hochschule Aachen, 1965.     

Structural effects of the lone pair on lead(II), and parallels with the coordination geometry of mercury(II). Does the lone pair on lead(II) form H-bonds? Structures of the lead(II) and mercury(II) complexes of the pendant-donor macrocycle DOTAM (1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane)

The synthesis and structures of [Pb(DOTAM)](ClO4)2.4.5H2O (1) and [Hg(DOTAM)](ClO4)2.0.5CH3OH.1.5H2O (2) are reported, where DOTAM is 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane. Compound 1 is triclinic, space group P, a = 12.767(3) A, b = 13.528(2) A, c = 18.385(3) A, alpha = 101.45(2) degrees, beta = 93.32(2) degrees, gamma = 90.53(2) degrees, Z = 4, R = 0.0500. Compound 2 is monoclinic, space group Cc, a = 12.767(3) A, b = 13.528(2) A, c = 18.385(3) A, beta = 101.91(2) degrees, Z = 4, R = 0.0381. The Pb(II) ion in 1 has an average Pb-N = 2.63 A to four N-donors from the macrocyclic ring, and four O-donors (average Pb-O = 2.77 A) from the amide pendant donors of the macrocycle, with a water molecule placed with Pb-O = 3.52 A above the proposed site of the lone pair (Lp) on Pb. The Hg(II) in 2 appears to be only six-coordinate, with four Hg-N bond lengths averaging 2.44 A, and two Hg-O from pendant amide donors at 2.41 A. The other two amide donors appear to be noncoordinating, with Hg-O distances of 2.74 and 2.82 A. A water situated 3.52 A above the proposed site of the lone pair on Pb(II) in 1 is oriented in such a way that it might be thought to be forming a Pb-Lp.H-O-H hydrogen bond. It is concluded that that this is not an H-bond, but that the presence of the lone pair allows a closer approach of the hydrogens to Pb than would be true otherwise. The structural analogy in the VSEPR sense between Pb(II), which has the 5d(10)6s(2) outer electron structure, and the Hg(II) ion, which has the 5d10 structure, is examined. The tendency of Hg(II) toward linear coordination, with two short Hg-L bonds (L = ligand) at 180 degrees to each other, and other donor groups at roughly 90 degrees to this and at much longer bond distances, is paralleled by Pb(II). One of the short Hg-L bonds is replaced in the Pb(II) structures by the lone pair (Lp), which is opposite the short Pb-L bond, or in some cases 2-4 shorter Pb-L bonds.     

Banana Peel: A Potential Substrate for Laccase Production by <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> VkJ2.4.5 in Solid-State Fermentation

In solid-state fermentation, among various solid supports evaluated, banana peel was found to be an ideal support and resulted into higher levels of laccase (6281.4 ± 63.60 U l⁻¹) along with notable levels of manganese peroxidase production (1339.0 ± 131.23 U l⁻¹) by Aspergillus fumigatus VkJ2.4.5. Maximum levels of laccase was achieved under derived conditions consisting of 80% of moisture level, 6 days of incubation period, 6% inoculum level, and an aeration level of 2.5 l min⁻¹. A column-tray bioreactor was designed to scale up and economize the enzyme production in three successive cycles of fermentation using the same fungal biomass. Thermal and pH stability profiles revealed that enzyme was stable up to 50°C and at varying pH range from 5–9 for up to 2 h. The apparent molecular weight of laccase was found to be 34 ± 1 kDa. MALDI-TOF/TOF analysis of the protein showed significant homology with maximum identity of 67% to other laccases reported in database.     

Synthesis and antimalarial effects of N,N-dialkyl-6-(substituted phenyl)-1,2,4,5-tetrazin-3-amines

The synthesis of a series of N,N-dialkyl-6-(substituted phenyl)-1,2,4,5-tetrazin-3-amines (IV) by two routes is described. The first route (Scheme I) involved the oxidative cyclization of formazans (II) to 3-bromo-6-(substituted phenyl)-1,2,4,5-tetrazines (III), followed by treatment with amines. The second (Scheme II) utilized the treatment of 3-(methylthio)-6-(substituted phenyl)-1,2,4,5-tetrazines (VII) with amines to provide the desired products. The intermediate 3-(methylthio)-6-(substituted phenyl)-1,2,4,5-tetrazines (VII) were obtained by thiobenzoylation of hydrazinecarbohydrazonothioic acid methyl ester with [[(substituted phenyl)thioxomethyl]thio]-acetic acids (V) to afford the 1,2-dihydro-3-(methylthio)-6-(substituted phenyl)-1,2,4,5-tetrazines (VI). Oxidation with bromine in acetic acid provided the desired intermediates. The target 6-(substituted phenyl)-1,2,4,5-tetrazin-3-amines (IV) displayed modest antimalarial activity.     

3-(2-二唑啉基)-色酮类化合物的合成研究

报道了取代的邻羟基苯乙酮(1a～1e)经Vilsmeier-Haack反应一步制得3-醛基色酮(2a～2e),2a～2e与取代的芳酰肼(3a～3c)缩合制得15个酰腙类化合物(4a～4o),4a～4o在醋酸酐作用下关环得15个3-(2-苝二唑啉基)-色酮(5a～5o),并通过元素分析,IR,~1H NMR和MS诺数据确证了上述化合物的结构。     

O-H...O interactions involving doubly charged anions: charge compression in carbonate-bicarbonate crystals

The O-H...O interaction formed by the anions HCO(3)(-) and CO(3)(2-) has been investigated on the basis of data retrieved from the Inorganic Crystal Structure Database (ICSD) and by means of ab initio computations. It has been shown that the O-H...O separations associated with HCO(3)(-)...(3)(2-) interactions are shorter than those found in crystals containing hydrogen carbonate monoanions such as HCO(3)(-)...HCO(3)(-). Ab initio MP2/6-311G++(2d,2p) computations on the crystal Na(3)(HCO(3))(CO(3)).2H(2)O have shown that the interaction between the monoanion donor and the dianion acceptor, for example HCO(3)(-)...CO(3)(2-), is more repulsive than that between singly charged ions, for example HCO(3)(-)...HCO(3)(-), but is largely overcompensated for by anion-cation electrostatic attractions. The shortening of the (-)O-H...O(2-) interaction relative to the (-)O-H...O(-) interaction has been explained as a consequence of the increased charge compression, that is of the stronger cation-anion interactions established by the CO(3)(2-) dianions with respect to those established by monoanions, and does not reflect an increase in the strength of the (-)O-H ...O(-) interaction. To expand the structural sample in the crystal packing analysis, the structure of the novel mixed salt K(2)Na(HCO(3))(CO(3)).2H(2)O has been determined by single-crystal X-ray diffraction and compared with the structure of the salt Na(3)(HCO(3))(CO(3)).2H(2)O used in the computations.     

Kinetics and mechanisms of CF3CHFOCH3, CF3CHFOC(O)H, and FC(O)OCH3 reactions with OH radicals

The kinetics and mechanism of oxidation of CF3CHFOCH3 was studied using an 11.5-dm3 environmental reaction chamber. OH radicals were produced by UV photolysis of an O3-H2O-He mixture at an initial pressure of 200 Torr in the chamber. The rate constant of the reaction of CF3CHFOCH3 with OH radicals (k1) was determined to be (1.77 +/- 0.69) x 10(-12) exp[(-720 +/- 110)/T] cm3 molecule(-1)(s-1) by means of a relative rate method at 253-328 K. The mechanism of the reaction was investigated by FT-IR spectroscopy at 298 K. CF3CHFOC(O)H, FC(O)OCH3, and COF2 were determined to be the major products. The branching ratio (k1a/k1b) for the reactions CF3CHFOCH3 + OH --> CF3CHFOCH2* + H2O (k1a) and CF3CHFOCH3 + OH --> CF3CF*OCH3 + H2O (k1b) was estimated to be 4.2:1 at 298 K from the yields of CF3CHFOC(O)H, FC(O)OCH3, and COF2. The rate constants of the reactions of CF3CHFOC(O)H (k2) and FC(O)OCH3 (k3) with OH radicals were determined to be (9.14 +/- 2.78) x 10(-13) exp[(-1190 +/- 90)/T] and (2.10 +/- 0.65) x 10(-13) exp[(-630 +/- 90)/T] cm3 molecule(-1)(s-1), respectively, by means of a relative rate method at 253-328 K. The rate constants at 298 K were as follows: k1 = (1.56 +/- 0.06) x 10-13, k2 = (1.67 +/- 0.05) x 10-14, and k3 = (2.53 +/- 0.07) x 10-14 cm3 molecule(-1)(s-1). The tropospheric lifetimes of CF3CHFOCH3, CF3CHFOC(O)H, and FC(O)OCH3 with respect to reaction with OH radicals were estimated to be 0.29, 3.2, and 1.8 years, respectively.     

A convenient synthesis of 3-(4-pyridinyl)quinolines

3-(Arylamino)-2-(4-pyriclinyl)acroleins 3 prepared by reacting anilines 1 with 3-(dimethylamino)-2-(4-pyridinyl)acrolein ( 2 ) were cyclized with phosphorus oxychloride or acetic acid to give 3-(4-pyridinyl)quinolines 4 .     

Synthesis of 3-azido-2,3,6-trideoxy-beta-D-arabino-hexopyranosyl pyranonaphthoquinone analogues of medermycin

The synthesis of an isomeric mixture of 4-O-acetyl-3-azido-2,3,6-trideoxy-beta-D-arabino-hexopyranosyl analogues 6 of the C-glycosylpyranonaphthoquinone antibiotic medermycin is described. The key 3-acetyl-6-(4-O-acetyl-3-azido-2,3,6-trideoxy-beta-D-arabino- hexopyranosyl)-5-methoxy-1,4-naphthoquinone 8 was prepared via Stille coupling of 6-(3-azido-2,3,6-trideoxy-beta-D-arabino-hexopyranosyl)-3-bromo-1,4- naphthoquinone 17 with (alpha-ethoxyvinyl)tributyl-stannane followed by hydrolysis and oxidation of the resultant hydroquinone 18. Bromonaphthoquinone 17 in turn was afforded by oxidative demethylation of 6-(4-O-acetyl-3-azido-2,3,6-trideoxy-beta-D-arabino-hexopyranosyl)-3- bromo-1,4,5-trimethoxynaphthalene 16 formed by regioselective bromination of 6-(4-acetyl-3-azido-2,3,6-trideoxy- beta-D-arabino-hexopyranosyl)-1,4,5-trimethoxynaphthalene 10. This latter naphthalene 10 was prepared via direct C-glycosylation of naphthol 12 with glycosyl donor 11 using BF3.Et2O in acetonitrile. The regioselectivity of the bromination of naphthalene 10 was independently determined by reductive monomethylation of the 6-(4-O-acetyl-3-azido-2,3,6-trideoxy-beta-D-arabino- hexopyranosyl)-5-methoxy-1,4-naphthoquinone 22 to naphthol 23 followed by selective ortho bromination to bromide 24 and methylation to 16. Attempts to effect acetylation of 6-(4-O-acetyl-3-azido-2,3,6-trideoxy-beta-D-arabino- hexopyranosyl)-3-bromo-1,4,5-trimethoxynaphthalene 16 and 3-bromo-6-(3-dimethylamino-2,3,6-trideoxy-beta-D-arabino- hexopyranosyl)-1,4,5-trimethoxynaphthalene 26 via Stille coupling with (alpha-ethoxyvinyl)tributylstannane were low yielding thereby establishing the necessity to use an azido group as a latent dimethylamino group and a more electrophilic bromonaphthoquinone as the coupling partner for the Stille reaction. Addition of 2-trimethylsilyloxyfuran 9 to 3-acetyl-6-(4-O-acetyl-3-azido-2,3,6-trideoxy-beta-D-arabino-hexopyranosyl)- 5-methoxy-1,4-naphthoquinone 8 afforded the furofuran adducts 7 and 19 as an inseparable mixture of diastereomers. Oxidative rearrangement of this diastereomeric mixture using ceric ammonium nitrate afforded the inseparable diastereomeric furonaphthopyrans 6 and 20.     

Asymmetric synthesis of (1R,2S,3R)-3-methylcispentacin and (1S,2S,3R)-3-methyltranspentacin by kinetic resolution of tert-butyl (+/-)-3-methylcyclopentene-1-carboxylate

Conjugate addition of lithium dibenzylamide to tert-butyl (+/-)-3-methylcyclopentene-1-carboxylate occurs with high levels of stereocontrol, with preferential addition of lithium dibenzylamide to the face of the cyclic alpha,beta-unsaturated acceptor anti- to the 3-methyl substituent. High levels of enantiorecognition are observed between tert-butyl (+/-)-3-methylcyclopentene-1-carboxylate and an excess of lithium (+/-)-N-benzyl-N-alpha-methylbenzylamide (10 eq.) (E > 140) in their mutual kinetic resolution, while the kinetic resolution of tert-butyl (+/-)-3-methylcyclopentene-1-carboxylate with lithium (S)-N-benzyl-N-alpha-methylbenzylamide proceeds to give, at 51% conversion, tert-butyl (1R,2S,3R,alphaS)-3-methyl-2-N-benzyl-N-alpha-methylbenzylaminocyclopentane-1-carboxylate consistent with E > 130, and in 39% yield and 99 +/- 0.5% de after purification. Subsequent deprotection by hydrogenolysis and ester hydrolysis gives (1R,2S,3R)-3-methylcispentacin in > 98% de and 98 +/- 1% ee. Selective epimerisation of tert-butyl (1R,2S,3R,alphaS)-3-methyl-2-N-benzyl-N-alpha-methylbenzylaminocyclopentane-1-carboxylate by treatment with KO'Bu in 'BuOH gives tert-butyl (1S,2S,3R,alphaS)-3-methyl-2-N-benzyl-N-alpha-methylbenzylaminocyclopentane-1-carboxylate in quantitative yield and in > 98% de, with subsequent deprotection by hydrogenolysis and ester hydrolysis giving (1S,2S,3R)-3-methyltranspentacin hydrochloride in > 98% de and 97 +/- 1% ee.     

Solvent-free reaction of 3-aryl-6-(3-nitrophenyl)-1,2,4-triazines with 4-(cyclohex-1-en-1-yl)morpholine

The aza-Diels–Alder reaction of 3-aryl-6-(3-nitrophenyl)-1,2,4-triazines with 4-(cyclohex-1-en-1-yl)morpholine as dienophile was accompanied by reduction of the nitro group to amino. In the reaction of 3-(4-methoxyphenyl)-6-(3-nitrophenyl)-1,2,4-triazine with 4-(cyclohex-1-en-1-yl)morpholine, 3-[3-(4-methoxyphenyl)-1,2,4-triazin-6-yl)aniline was formed together with the cycloaddition product.     

Structure and reactivity of bis(silyl) dihydride complexes (PMe(3))(3)Ru(SiR(3))(2)(H)(2): model compounds and real intermediates in a dehydrogenative C-Si bond forming reaction

A series of stable complexes, (PMe(3))(3)Ru(SiR(3))(2)(H)(2) ((SiR(3))(2) = (SiH(2)Ph)(2), 3a; (SiHPh(2))(2), 3b; (SiMe(2)CH(2)CH(2)SiMe(2)), 3c), has been synthesized by the reaction of hydridosilanes with (PMe(3))(3)Ru(SiMe(3))H(3) or (PMe(3))(4)Ru(SiMe(3))H. Compounds 3a and 3c adopt overall pentagonal bipyramidal geometries in solution and the solid state, with phosphine and silyl ligands defining trigonal bipyramids and ruthenium hydrides arranged in the equatorial plane. Compound 3a exhibits meridional phosphines, with both silyl ligands equatorial, whereas the constraints of the chelate in 3c result in both axial and equatorial silyl environments and facial phosphines. Although there is no evidence for agostic Si-H interactions in 3a and 3b, the equatorial silyl group in 3c is in close contact with one hydride (1.81(4) A) and is moderately close to the other hydride (2.15(3) A) in the solid state and solution (nu(Ru.H.Si) = 1740 cm(-)(1) and nu(RuH) = 1940 cm(-)(1)). The analogous bis(silyl) dihydride, (PMe(3))(3)Ru(SiMe(3))(2)(H)(2) (3d), is not stable at room temperature, but can be generated in situ at low temperature from the 16e(-) complex (PMe(3))(3)Ru(SiMe(3))H (1) and HSiMe(3). Complexes 3b and 3d have been characterized by multinuclear, variable temperature NMR and appear to be isostructural with 3a. All four complexes exhibit dynamic NMR spectra, but the slow exchange limit could not be observed for 3c. Treatment of 1 with HSiMe(3) at room temperature leads to formation of (PMe(3))(3)Ru(SiMe(2)CH(2)SiMe(3))H(3) (4b) via a CH functionalization process critical to catalytic dehydrocoupling of HSiMe(3) at higher temperatures. Closer inspection of this reaction between -110 and -10 degrees C by NMR reveals a plethora of silyl hydride phosphine complexes formed by ligand redistribution prior to CH activation. Above ca. 0 degrees C this mixture converts cleanly via silane dehydrogenation to the very stable tris(phosphine) trihydride carbosilyl complex 4b. The structure of 4b was determined crystallographically and exhibits a tetrahedral P(3)Si environment around the metal with the three hydrides adjacent to silicon and capping the P(2)Si faces. Although strong Si.HRu interactions are not indicated in the structure or by IR, the HSi distances (2.00(4) - 2.09(4) A) and average coupling constant (J(SiH) = 25 Hz) suggest some degree of nonclassical SiH bonding in the RuH(3)Si moiety. The least hindered complex, 3a, reacts with carbon monoxide principally via an H(2) elimination pathway to yield mer-(PMe(3))(3)(CO)Ru(SiH(2)Ph)(2), with SiH elimination as a minor process. However, only SiH elimination and formation of (PMe(3))(3)(CO)Ru(SiR(3))H is observed for 3b-d. The most hindered bis(silyl) complex, 3d, is extremely labile and even in the absence of CO undergoes SiH reductive elimination to generate the 16e(-) species 1 (DeltaH(SiH)(-)(elim) = 11.0 +/- 0.6 kcal x mol(-)(1) and DeltaS(SiH)(-)(elim) = 40 +/- 2 cal x mol(-)(1) x K(-)(1); Delta = 9.2 +/- 0.8 kcal x mol(-)(1) and Delta = 9 +/- 3 cal x mol(-)(1).K(-)(1)). The minimum barrier for the H(2) reductive elimination can be estimated, and is higher than that for silane elimination at temperatures above ca. -50 degrees C. The thermodynamic preferences for oxidative additions to 1 are dominated by entropy contributions and steric effects. Addition of H(2) is by far most favorable, whereas the relative aptitudes for intramolecular silyl CH activation and intermolecular SiH addition are strongly dependent on temperature (DeltaH(SiH)(-)(add) = -11.0 +/- 0.6 kcal x mol(-)(1) and DeltaS(SiH)(-)(add) = -40 +/- 2 cal.mol(-)(1) x K(-)(1); DeltaH(beta)(-CH)(-)(add) = -2.7 +/- 0.3 kcal x mol(-)(1) and DeltaS(beta)(-CH)(-)(add) = -6 +/- 1 cal x mol(-)(1) x K(-)(1)). Kinetic preferences for oxidative additions to 1 - intermolecular SiH and intramolecular CH - have been also quantified: Delta = -1.8 +/- 0.8 kcal x mol(-)(1) and Delta = -31 +/- 3 cal x mol(-)(1).K(-)(1); Delta = 16.4 +/- 0.6 kcal x mol(-)(1) and Delta = -13 +/- 6 cal x mol(-)(1).K(-)(1). The relative enthalpies of activation (-)(1) x K(-)(1)). Kinetic preferences for oxidative additions to 1 - intermolecular SiH and intramolecular CH - have been also quantified: Delta (H)SiH(add) = 1.8 +/- 0.8 kcal x mol(-)(1) and Delta S((SiH-add) =31+/- 3 cal x mol(-)(1) x K(-)(1); Delta S (SiH -add) = 16.4 +/- 0.6 kcal x mol(-)(1) and =Delta S (SiH -CH -add) =13+/- 6 cal x mol(-)(1) x K(-)(1). The relative enthalpies of activation are interpreted in terms of strong SiH sigma-complex formation - and much weaker CH coordination - in the transition state for oxidative addition.     

Lipase-catalyzed resolution of (2R*,3S*)- and (2R*,3R*)-3-methyl-3-phenyl-2-aziridinemethanol at low temperatures and determination of the absolute configurations of the four stereoisomers

[reaction: see text] Lipase-catalyzed resolution of (2R*,3S*)-3-methyl-3-phenyl-2-aziridinemethanol, (+/-)-2, at low temperatures gave synthetically useful (2R,3S)-2 and its acetate (2S,3R)-2a with (2S)-selectivity (E = 55 at -40 degrees C), while a similar reaction of (2R*,3R*)-3-methyl-3-phenyl-2-aziridinemethanol, (+/-)-3, gave (2S,3S)-3 and its acetate (2R,3R)-3a with (2R)-selectivity (E = 73 at -20 degrees C). Compound (+/-)-2 was prepared conveniently via diastereoselective addition of MeMgBr to tert-butyl 3-phenyl-2H-azirine-2-carboxylate, (+/-)-1a, which was successfully prepared by the Neber reaction of oxime tosylate of tert-butyl benzoyl acetate 7a. The tert-butyl ester was requisite to promote this reaction. For determination of the absolute configuration of (2S,3R)-2a, enantiopure (2S,3R)-2 was independently prepared in three steps involving diastereoselective methylation of 3-phenyl-2H-azirine-2-methanol, (S)-10, with MeMgBr. The absolute configuration of (2S,3S)-3 was determined by X-ray analysis of the corresponding N-(S)-2-(6-methoxy-2-naphthyl)propanoyl derivative (S,S,S)-13.     

Synthesis, structural characterization, and antiinflammatory activity of triethylphosphinegold(I) sulfanylpropenoates of the type [(AuPEt3)2xspa] [H2xspa = 3-(aryl)-2-sulfanylpropenoic acid]: an (H2O)6 cluster in the lattice of the complexes [(AuPEt3)2xspa] x 3 H2O

Gold complexes of the type [(AuPEt3)2xspa] were prepared by reacting AuPEt3Cl in basic media with the 3-(aryl)-2-sulfanylpropenoic acids H2xspa [x = p, Clp, -o-mp, -p-mp, -o-hp, -p-hp, diBr-o-hp, f, t, -o-py; p = 3-phenyl, Clp = 3-(2-chlorophenyl)-, -o-mp = 3-(2-methoxyphenyl)-, -p-mp = 3-(4-methoxyphenyl)-, -o-hp = 3-(2-hydroxyphenyl)-, -p-hp = 3-(4-hydroxyphenyl)-, diBr-o-hp = 3-(3,5- dibromo-2-hydroxyphenyl)-, f = 3-(2-furyl)-, t = 3-(2-thienyl)-, -o-py = 3-(2-pyridyl); spa = 2-sulfanylpropenoato], and 2-cyclopentylidene-2-sulfanylacetic acid (H2cpa). The complexes were characterized by spectroscopic methods (IR, (1)H, (13)C and (31)P NMR) and mass spectrometry, and the complexes [(AuPEt3)2pspa] x 3 H2O, [(AuPEt3)2-p-hpspa] x 3 H2O, [(AuPEt3)2tspa)] x 3 H2O, and [(AuPEt3)2-o-hpspa] by X-ray diffractometry. The crystals of the first three complexes contain (H2O)6 clusters hydrogen bonded to [(AuPEt3)2xspa]2 dimer units, whereas in the -o-hpspa derivative the hydrogen bonds are between the monomer [(AuPEt3)2-o-hpspa] units. The antiinflammatory activity of the complexes against plantar edema induced by carrageenan in rats is generally significant, with the values for the o-hpspa and tspa derivatives being particularly high.     

Optically active antifungal azoles. XI. An alternative synthetic route for 1

New routes for the synthesis of the optically active antifungal triazoles 1-[(1R,2R)-2-(2,4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl]-3-[4-(1H-1-tetrazolyl)phenyl]-2-imidazolidinone (1b) and the 3-14-(1H-1,2,3-triazol-1-yl)phenyl]-2-imidazolidinone analog (1a) that possess an imidazolidine nucleus were established. The key synthetic intermediates, (2R,3R)-3-(2,2-diethoxvethyl)amino-2-(2,4-difluorophenyl)-1-(1H1,2,4-triazol-1-yl)-2-butanol (8) and (2R,3R)-2-(2,4-difiuorophenyl)-3-(2-h ydroxyethyl)amino-1-(1H-1,2,4-triazol-1-yl)-2-butanol (14), were prepared by the ring-opening reaction of the oxirane (2) with the corresponding 2-substituted ethylamines. The acetal (8) was converted to the imidazolidinones (1a, b) by condensation with the carbamates (10a, b) followed by treatment with hydrochloric acid and subsequent catalytic hydrogenation. The candidate selected for the clinical trials, 1b (TAK-456), was alternatively prepared from the hydroxyethylamino intermediate (14) via two reaction steps: condensation with the carbamate (10b) to the urea (15) and subsequent cyclization to the imidazolidinones. This newly developed synthetic route could be applied to a large scale preparation of 1b.     

A New Convenient Method for the Resolution of 1, 1''''-Binaphthalene-2, 2''''-diol Via a Phosphite Using (-)-Menthol as Resolving Agent

Optically active 1,1-binaphthalene-2, 2-diol has become a quite important chiral source in different fields of chirotechnology, especially in asymmetric synthesis1. Its synthesis and resolution has been extensively studied and various resolution methods have been reported2. Among the reported resolution methods, the following three, namely, via the formation of phosphoric acid derivatives3, boric acid derivatives4 and inclusion complexes5, are the most important. OHOH+_( )-1(-)-(S)-1(+)-(R)…