Expeditious synthesis of novel NK1 antagonists based on a 1,2,4-trisubstituted cyclohexane

A stereoselective asymmetric route to novel potent NK₁ antagonists based on a 1,2,4-trisubstituted cyclohexane core is discussed.     

Oxidative dehydrogenation of crotonaldehyde overK2HPMo12O40catalyst

Summary The oxidative dehydrogenation of crotonaldehyde to furan and maleic anhydride was carried out over K₂HPMo₁₂O₄₀catalyst. A positive effect of water vapor on furan formation is explained by ability of the catalyst to isomerize 2E- to 2Z-crotonaldehyde.</o:p>     

Synthesis of 1H-pyrrolo[3,2-c]quinoline derivatives via palladium-catalyzed heteroannulation of 2-aryl-3-iodo-4-(phenylamino)quinolines and 4-(N,N-allylphenylamino)-2-aryl-3-iodoquinolines

Palladium(0)/copper iodide catalyzed Sonogashira cross-coupling of 2-aryl-3-iodo-4-(phenylamino)quinolines with terminal alkynes afforded series of 1,2,4-trisubstituted 1H-pyrrolo[3,2-c]quinolines in a single-step operation. Conversely, the 4-(N,N-allylphenylamino)-2-aryl-3-iodoquinoline derivatives were found to undergo PdCl₂(PPh₃)₂/CuI catalyzed intramolecular Heck reaction to yield the corresponding 1,3,4-trisubstituted 1H-pyrrolo[3,2-c]quinolines.     

Direct synthesis of tetrahydropyrans via one-pot Babier-Prins cyclization of allylbromide with carbonyl compounds promoted by RTILs BPyX/SnX′2 or BBIMBr/SnBr2

Tetrahydropyran compounds can be directly synthesized from allylbromide and carbonyl compounds by means of one-pot Babier-Prins cyclization promoted by BPyX/SnX′₂ or BBIMBr/SnBr₂ complex (functionalized RTILs) under solvent-free conditions. 2,6-Homo-bissubstituted- and 2,6,6-trisubstituted, especially 6-(spirocycloalkyl)-, tetrahydropyran compounds can be prepared in good yields.     

Synthesis of pyrylium salts from trisubstituted 1,4-pentadiyn-3-ols with HClO4

The synthesis of 2,4,6-trisubstituted pyrylium salts from 1,3,5-trisubstituted 1,4-pentadiyn-3-ols with HClO₄ is reported for the first time.     

An efficient stereoselective synthesis of (E)- and (Z)-trisubstituted alkenes from unactivated Baylis-Hillman adducts using NaBH4/CuCl2·2H2O

A convenient and facile stereoselective synthesis of (E)- and (Z)-trisubstituted alkenes has been achieved by treatment of unactivated Baylis-Hillman adducts with NaBH₄ in the presence of CuCl₂·2H₂O at room temperature for 15 min.     

Crystal structures and thermal properties of Ba(1,2,4-t-Bu3C5H2)2 and Sr(1,2,4-t-Bu3C5H2)2: Precursors for atomic layer deposition

Sterically hindered Lewis base free bis(1,2,4-tri-tert-butylcyclopentadienyl)strontium (1) and bis(1,2,4-tri-tert-butylcyclopentadienyl)barium (2) were synthesized using the common metathesis route and characterized with NMR, MS, TGA/SDTA and XRD. Compound 1 crystallized as a monomer with typical bent structure. Asymmetric unit contains two independent slightly different Sr(t-Bu₃C₅H₂)₂ molecules with Cp(centroid)-Sr-Cp(centroid) angles of 165.1° and 169.4°. Depending on the way of crystallization two polymorphs (2a and 2b) were observed for Ba(t-Bu₃C₅H₂)₂. On sublimation Ba(t-Bu₃C₅H₂)₂ crystallizes as chains in which one methyl group of each Ba(t-Bu₃C₅H₂)₂ unit interacts with neighboring Ba(t-Bu₃C₅H₂)₂ unit’s barium atom. Slow crystallization of waxy evaporation residue of toluene solution results in monoclinic crystals (2b) whose asymmetric unit contains four slightly different individual Ba(t-Bu₃C₅H₂)₂ molecules with Cp(centroid)-Ba-Cp(centroid) angles of 161.3-164.9°. Both compounds prepared are volatile, thermally stable and reactive and thus suitable precursors for atomic layer deposition of thin films.     

Synthesis of di- and trisubstituted 1,2,4-triazoles containing indole fragments

The reaction of imino esters of indole-series acids with acid hydrazides gave N₍₁₎-acylamidrazones, which, during heating, were converted to 3,5-disubstituted 1H-1,2,4-triazoles containing indole fragments. Compounds of this type were also synthesized by the reaction of indolyl-containing 2,5-disubstituted 1,3,4-oxadiazoles with formamide. Condensation of 2,5-disubstituted 1,3,4-oxadiazoles with aniline gave 3,4,5-trisubstituted 4H-1,2,4-triazoles containing indolyl radicals. Cyclocondensation of N₍₁₎-phenylamidrazones of indole-series acids with benzoyl chloride gave 1,3,5-trisubstituted 1H-1,2,4-triazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 189–196, February, 1993.     

Cu(N-N)2Cl2 and Cu(N-N-N)Cl2 and HgCl2 building blocks in the synthesis of coordination compounds—X-ray studies and magnetic properties

A series of complexes containing Cu(N-N)₂Cl₂ (N-N=bis(pyrazol-1-yl)methane (bpzm), bis(3,5dimethylpyrazol-1-yl)methane (bdmpzm), 2,2-dipyridylamine (dpa), 5,6-diphenyl-3-(2-pyridyl)-1,2,4-trazine (dppt) and 2,2′-bipyridine (bipy)), Cu(N-N-N)Cl₂ (N-N-N=2,2′:6′,2″-terpyridine (terpy)) and HgCl₂ building blocks have been synthesized and structurally characterized. Increase in structural dimensionality is observed for [Cu(bpzm)₂][HgCl₄], [Cu(dpa)₂][HgCl₃]₂ and [Cu(terpy)(μ-Cl)HgCl₃] compounds. No coordination polymers have formed in the case of bis(3,5dimethylpyrazol-1-yl)methane, 5,6-diphenyl-3-(2-pyridyl)-1,2,4-trazine and 2,2′-bipyridine. The [Cu(bpzm)₂][HgCl₄] and [Cu(terpy)(μ-Cl)HgCl₃] complexes have been studied by magnetic measurements.     

Toluene methylation on AlPO4-Al2O3 catalysts (5–15 wt.% Al2O3)

The alkylation of toluene with methanol over AlPO₄-Al₂O₃ (5–15 wt.% Al₂O₃) catalysts produces a mixture of xylenes (XYL) although trimethylbenzenes (TMB) were also found. The TMB selectivity increased with temperature at the expense of XYL selectivity. Isomer distribution was approximately 48, 24 and 27 mol% foro-, m- andp-XYL, and 74, 26 and 0 mol% for 1,2,3-, 1,2,4- and 1,3,5-TMB, both quite different from the equilibrium isomer composition. The catalytic activity increased with alumina content, however, it decreased on increasing the calcination temperature in the 923–1273 K range. Good correlations between catalytic activity and the increase in acidic properties with Al₂O₃ loading (as determined by base chemisorption, in the gas phase,versus pyridine and 2,6-dimethylpyridine) have been obtained.     

Liquid phase oxidation of crotonaldehyde to furan by aqueous CuCl2

Liquid phase oxidative cyclization of crotonaldehyde (2-butenal) to furan was for the first time found to proceed effectively in a CuCl₂, CuCl or PdCl₂ or PdCl₂ aqueous solution containing alkali or ammonium halides and HCl as additives in the temperature range of 350–378 K. Chlorides of iron, manganese and gold were inactive. CuCl has almost the same activity as CuCl₂, showing that the reaction can proceed catalytically.     

Synthesis of the C5-C30 fragment of cyclodidemniserinol trisulfate via I2-mediated deprotection and ring closure tandem reaction

The marine natural product cyclodidemniserinol trisulfate displayed moderate HIV-1 integrase inhibitory activity. Its novel structure triggered our interest to synthesize it. In our total synthesis effort, the natural product was dissected into four fragments based on the rational retrosynthetic analysis. All four fragments were successfully prepared with orthogonal protection. And the assembly of fragment A and B furnished the C₅-C₃₀ key subunit by employing the I₂-mediated deprotection and intramolecular ketal formation tandem reaction in the presence of NaHCO₃ in MeCN. Our work provided flexible and practical approaches to synthesize and derive the 3,5,7-trisubstituted 6,8-dioxabicyclo [3.2.1] octane based analogs to search for new structure HIV-1 integrase inhibitors.     

Synthesis, structure and optical properties of new organic-inorganic haloplumbates complexes (C5H10N3)PbX4 (X=Br, Cl), (C2H2N4)PbBr3

Layered organic-inorganic composite materials (C₅H₁₀N₃)PbX₄ (X=Br 1, Cl 2) containing histaminium dications were grown via a solution-cooling process, and their structure and optical properties were determined. The organic ligand-histaminium introduced into the corner-sharing octahedra of the ‘PbX₄-layer’ contains both primary ammonium and imidazolium different from the traditionally primary amine found in this system. As comparison, another analogous amine of 3-amino-1,2,4-triazol was used as ligand to coordinate with PbBr₂ in acid solution. A novel complex (C₂H₂N₄)PbBr₃ (3) was obtained with zigzag PbBr₂ chains different from the PbX₄ layer in compound as 1 and 2. The hybrid (C₅H₁₀N₃)PbX₄ show exciton absorption at 339 nm for X=Cl and 419 nm for X=Br with the corresponding emission at 360 and 436 nm, respectively. The different PbBr₂ chain structure of compound 3 does not show photoluminescence.     

From N-sulfonyl,C-homoallyl-hydrazones to pyrazole and pyridazine (N2)-heterocycles: the ultimate aromatization process

Isomeric six- and five-membered (N₂)-aromatics, 6-methylpyridazines and 5-vinylpyrazoles, which energetic topological aromaticity is comparable to that of benzene, are shown to be efficiently produced by sequential isomerization–elimination processes from the corresponding 6-methylidene-1,4,5,6-tetrahydropyridazines and 5-vinylpyrazolines, respectively. The latter precursors are available from the same N-sulfonyl,C-homoallyl-hydrazone substrates by a suitable choice of previously reported conditions for Pd-catalyzed CH-oxidative C,N-ring closing processes. The generality of these cyclization, isomerization, and aromatization reactions, for which detailed mechanisms are proposed, provides a systematic access to wide ranges of 3,4,6-trisubstituted 6-methyl-1,4-dihydropyridazines and 6-methylpyridazines, and their 3,4,5-trisubstituted 5-vinylpyrazole isomers.     

3,5-二烷基-1,2,4-三唑衍生物构筑的两个Cu4I4簇配合物的合成、结构和荧光性质

以3,5-二甲(丙)基-4-氨基-1,2,4-三唑为配体,与CuI在H₂O/MeCN混合溶剂热合成了2个构型不同的Cu₄I₄超分子化合物{[Cu₂(aadmtrz) I₂]·CH₃CN}_n(1)和[Cu₂(dptrz) I]_n(2)(aadmtrz=4-((1-氨乙基)-氨基)-3,5-二甲基-1,2,4-三唑,dptrz=3,5-二丙基-1,2,4-三唑),并进行了元素分析,红外,X射线粉末衍射及单晶衍射等表征。2个配合物中Cu₄I₄构型不同,配合物1中,Cu₄I₄簇连结成一个8环椅式-椅式结构,通过配体连接成(4,4)二维菱形格子结构;而配合物2中,Cu₄I₄簇呈畸变的立方烷结构,构成了含有19.5%孔隙率三维孔洞聚合物,其结构可简化为(3,4)-连接的拓朴结构。同时,在常温下研究了2个配合物的固体荧光性质。     

Effect of solvent on the gelation properties of a metallo-organic polymer of [Fe(II) (4-octadecyl-1,2,4-triazole)3(ClO4)2]n

In this contribution we report on the preparation of thermally responsive supramolecular gels obtained through self-assembling of metallo-organic polymers of lipophilic Fe(II) complexes of 1,2,4-triazole functionalized with octadecyl chains ([Fe(II) (4-octadecyl-1,2,4-triazole)₃(ClO₄)₂]_n) in three organic solvents: toluene, cis-decalin and trans-decalin. A gel phase is formed in these solvents by cooling the homogeneous complex solutions below a well-defined temperature, the so-called gelation threshold. These gels are reversible as they form homogeneous solutions upon heating above the melting temperature. The systems have been characterized for their thermal and viscoelastic properties through differential scanning calorimetry and rheological experiments, respectively. The effect of the solvent type and concentration on the gelation behaviour of the metallo-organic polymer has been analysed. The results obtained point to structural differences and different gelation mechanisms for the gels prepared in different solvents and they also suggest the possibility to control the spin-crossover transition temperature associated to the sol-gel transition.     

3,5-二烷基-1,2,4-三唑衍生物构筑的两个Cu4I4簇配合物的合成、结构和荧光性质

以3,5-二甲（丙）基-4-氨基-1,2,4-三唑为配体,与CuI在H₂O/MeCN混合溶剂热合成了2个构型不同的Cu₄I₄超分子化合物{[Cu₂（aadmtrz）I₂]·CH₃CN}_n （1）和[Cu₂（dptrz）I]_n （2）（aadmtrz=4-（（1-氨乙基）-氨基）-3,5-二甲基-1,2,4-三唑,dptrz=3,5-二丙基-1,2,4-三唑）,并进行了元素分析,红外,X射线粉末衍射及单晶衍射等表征。2个配合物中Cu₄I₄构型不同,配合物1中,Cu₄I₄簇连结成一个8环椅式-椅式结构,通过配体连接成（4,4）二维菱形格子结构;而配合物2中,Cu₄I₄簇呈畸变的立方烷结构,构成了含有19.5%孔隙率三维孔洞聚合物,其结构可简化为（3,4）-连接的拓朴结构。同时,在常温下研究了2个配合物的固体荧光性质。     

Highly regioselective [2+2+2] cycloaddition of terminal alkynes catalyzed by titanium complexes of p-tert-butylthiacalix[4]arene

Mono- and dinuclear titanium complexes of p-tert-butylthiacalix[4]arene were applied as a catalyst for [2+2+2] cycloaddition of terminal alkynes. They showed high catalytic activity and regioselectivity toward 1,3,5-trisubstituted benzenes over 1,2,4-trisubstituted isomers. The regioselectivity was rationalized in terms of the steric effect of the thiacalixarene skeleton and the coordination of the bridging sulfur atom to the titanium center.     

Ruthenium-catalyzed coupling reaction of 2,3,5-trisubstituted furans with aryl halides through C-H bond cleavages

A variety of functionalized furans were synthesized by way of a ruthenium-catalyzed coupling reaction of 2,3,5-trisubstituted furans with aryl halides through C-H bond cleavages. The feature of the reaction was facilitative preparation of furan derivatives good functional group tolerance. All reactions gave the desired products in moderate to good yields (56-89%) in the presences of [RuCl₂(p-cymene)] and K₂CO₃ in NMP at 120 °C.     

Theoretical investigation on regioselectivity of aromatic ketones in the addition with olefin catalyzed by RuH2(CO)(PPh3)3

Ab initio method is employed to study the structures of twelve aromatic ketones at HF/3-21G, HF/6-31G and HF/6-31G* levels, respectively. A theoretical analysis is also carried out to study the regioselectivity and reactivity of aromatic ketones in the addition with olefin catalyzed by RuH₂(CO)(PPh₃)₃. The results indicate that a U shape LUMO conjugation of aromatic ketones in a plane plays an important role in regioselectivity on the cleavage of β C-H bond and is a necessary factor to success of addition with olefin, and that steric effect is an indispensable factor in forming additional ortho-product. Meanwhile, electronic effect may influence the rate of addition for the structures alike which only have different replacements in the same site of aromatic ring, such as furan, thiophene and pyrole. A possible catalytic reaction mechanism is proposed that the addition of C-H bond may be carried out by a coordination of aromatic ketones with Ru complex.