Facile synthesis of 4-substituted 1,2,4,5-tetrahydro-1,4-benzodiazepin-3-ones by reductive cyclization of 2-chloro-N-(2-nitrobenzyl)acetamides

A facile and efficient method was developed for the synthesis of 1,2,4,5-tetrahydro-1,4-benzodiazepine-3-ones from 2-chloro-N-(2-nitrobenzyl)acetamides through a reductive cyclization using iron-ammonium chloride in ethanol–water in good yields. This method provides a simple approach to these benzodiazepine-3-ones which are of high value in the field of medicinal chemistry research.     

Synthesis of pseudopeptidic (S)-6-amino-5-oxo-1,4-diazepines and (S)-3-benzyl-2-oxo-1,4-benzodiazepines by an Ugi 4CC Staudinger/aza-Wittig sequence

Sequential Ugi reaction between p-substituted arylglyoxals, alkylamines, cyclohexyl isocyanide and 3-azido-(S)-2-(tert-butoxycarbonylamino)propanoic acid, followed by a Staudinger/aza-Wittig cyclization in the presence of triphenylphosphine, gave rise to enantiomerically pure N-cyclohexyl 4-alkyl-2-aryl-5-oxo-(S)-6-(tert-butoxycarbonylamino)-4,5,6,7-tetrahydro-1H-1,4-diazepine-3-carboxamides, that can be useful for new drug design. By the same sequence, p-substituted benzaldehydes, 2-aminobenzophenone, cyclohexyl isocyanide and (S)-3-phenyl-2-azidopropionic acid gave rise to N-cyclohexyl 2-((S)-3-benzyl-2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-1-yl)-(R/S)-2-arylacetamides.     

Base-promoted 1,3-dipolar cycloaddition reaction of nitrile oxides with methyl 1,4-dioxo-1,4-dihydronaphthalene-2-carboxylate for the construction of naphtho[2,3-d]isoxazole-4,9(3aH,9aH)-diones

A base mediated 1,3-dipolar cycloaddition reaction of methyl 1,4-dioxo-1,4-dihydronaphthalene-2-carboxylate with nitrile oxides in situ generated from N-hydroximoyl chlorides was achieved. With this developed protocol, a range of structurally diverse naphtho[2,3-d]isoxazole-4,9(3aH,9aH)-dione derivatives were smoothly obtained in high yields (up to 95%) with up to >20:1 regioselectivities and >20:1 diastereoselectivities under mild conditions. The promising applicability of the protocol was also demonstrated by the further transformations.     

Reactivity variations within Group 4 complexes of 1,4-di-tert-butyl-1,4-diazabuta-1,3-diene: Structures of [(C5H5)TiCl{(t-BuNCH)2}] and [(C5H5)2Zr{(t-BuNCH)2}]

The reactions of the metallocene dichlorides [(η⁵-C₅H₅)₂MCl₂], M = Ti and Zr, with the 1,4-di-tert-butyl-1,4-diazabuta-1,3-diene radical anion (lithium complex) in diethyl ether reveal a reactivity difference within the series, yielding [(C₅H₅)TiCl{(t-BuNCH)₂}] and [(C₅H₅)₂Zr{(t-BuNCH)₂}] through the elimination of Li(C₅H₅) and/or LiCl, respectively. We report the X-ray crystal structures of these complexes, and discuss their reactivity patterns and solution fluxional properties.     

1,3-Migration of a phenyl group in the conversion of (Me3Si)2(PhMe2Si)CSiMePhX into (Me3Si)2(Ph2MeSi)CSiMe2Y species

The finding that compounds of the type (Me₃Si)₂(PhMe₂Si)CSiMePhX react with electrophiles to give very predominantly rearranged products (Me₃Si)₂(Ph₂MeSi)CSiMe₂Y, which would be expected to be thermodynamically disfavoured, can be rationalized in terms of a mechanism in which the anchimerically-assisted departure of X⁻ gives the Ph-bridged cation [(Me₃Si)₂

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MePh]⁺ which is attacked by the nucleophile at the less hindered centre bearing two Me groups rather than that bearing one Me and one Ph group, with the outcome determined by kinetic rather than thermodynamic factors. Both (Me₃Si)₂(Ph₂MeSi)CSiMe₂Br and its isomer (Me₃Si)₂(PhMe₂Si)CSiMePhBr react with AgBF₄ in CH₂Cl₂ or Et₂O to give >95% of the fluoride (Me₃Si)₂(Ph₂MeSi)CSiMe₂F. Reaction of the bromide (Me₃Si)₂(PhMe₂Si)CSiMePhBr with AgO₂CCF₃ in Et₂O, and that of the hydride (Me₃Si)₂(PhMe₂Si)CSiMePhH with ICl in CCl₄, likewise give >95% of the rearranged (Me₃Si)₂(Ph₂MeSi)CSiMe₂O₂CCF₃ and (Me₃Si)₂(Ph₂MeSi)CSiMe₂Cl, respectively.     

Novel synthesis of 1,4-thiazin-2-one O-(tert-butyl) oximes and benzo[b][1,4]thiazin-2-one O-(tert-butyl) oximes in the presence of K2CO3/SiO2

A simple and efficient method was developed for the synthesis of 1,4-thiazin-2-one O-(tert-butyl) oximes and benzo[b][1,4]thiazin-2-one O-(tert-butyl) oximes from N-tert-butoxy acyl imidoyl bromides and 2-aminothiols in the presence of K₂CO₃/SiO₂. Twenty five novel compounds were readily synthesized in excellent yields using this procedure. The products possessed Z-stereochemistry with regard to the CN double bond. The reaction proceeded with initial substitution of bromine in the N-tert-butoxy acyl imidoyl bromides by mercapto groups in the presence of K₂CO₃/SiO₂, and subsequent intramolecular Schiff base formation.     

Stereospecific synthesis of conjugated (1E,3E)- and (1Z,3Z)-1,4-di(n-N,N-dimethylaminophenyl)-1,3-butadienes from 2-chloro-1-(n-N,N-dimethylaminophenyl)ethenes: fluorescence properties

The conjugated 1,4-di(n-N,N-dimethylaminophenyl)-1,3-butadienes (n=o-, m-, p-) were efficiently synthesised by homocoupling of the appropriate 2-chloro-1-(n-N,N-dimethylaminophenyl)ethene (n=o-, m-, p-) with stoichiometric amounts of zerovalent nickel complexes. The 1,3-butadienes were obtained as a mixture of stereoisomers, with independence of the starting E or Z chlorovinyl isomer. Moreover, the stereospecific (Z,Z) stereoisomer was obtained by partial hydrogenation of the corresponding 1,3-butadiyne, while the stereospecific (E,E) stereoisomer was obtained by exposure to the sunlight radiation of the (Z,Z) or the (Z,E) compound in ethanol.     

A facile method for the stereoselective preparation of (1E,3E)-4-substituted-1-amino-1,3-dienes via 1,4-elimination

The 1,4-elimination reaction of 1-amino-4-methoxy-(2Z)-alkenes is shown to proceed with high (1E,3E)-stereoselectivities to afford the corresponding 4-substituted-1-amino-1,3-dienes in good yield. The scope and stereochemical features of the synthetic method are described.     

Polymerization of 1,3-Butadiene Catalyzed by Cobalt(Ⅱ) and Nickel(Ⅱ) Complexes Bearing Pyridine-2-imidate Ligands

Cobalt and nickel complexes (1a-1d and 2a-2d, respectively) supported by 2-imidate-pyridine ligands were synthesized and used for 1,3-butadiene polymerization. The complexes were characterized by IR and element analysis, and complex 1a was further characterized by single-crystal X-ray diffraction. The solid state structure of complex 1a displayed a distorted tetrahedral geometry. Upon activation with ethylaluminum sesquichloride (EASC), all the complexes showed high activities toward 1,3-butadiene polymerization. The cobalt complexes produced polymers with high cis-1,4 contents and high molecular weights, while the nickel complexes displayed low cis-1,4 selectivity and the resulting polymers had low molecular weights. The catalytic activities of the complexes highly depended on the ligand structure. With the increment of polymerization temperature, the cis-1,4 content and the molecular weight of the resulting polymer decreased.     

Synthesis of conjugated (1E,3E)- and (1Z,3Z)-1,4-di(n-pyridyl) (or n-quinolyl)-1,3-butadienes from n-(2′-chloroethenyl)pyridine (or quinoline)

The homocoupling reaction between the conjugated n-(2-chloroethenyl)pyridine; n, 2-, 3- and 4- (or quinoline; n, 2- and 4-) mediated by zero-valent nickel complexes at room temperature affords to the corresponding 1,4-diaryl-1,3-butadiene, always as the 1E,3E stereoisomer. The yield in 1,4-diaryl-1,3-butadiene increases with the nickel catalyst and hence, the active zero-valent nickel catalyst is not regenerated during the homocoupling reaction.The stereospecific synthesis of (1Z,3Z)-1,4-di(4′-pyridyl)-1,3-butadiene stereoisomer was efficiently carried out by partial hydrogenation of the appropriate 1,4-di(4′-pyridyl)-1,3-butadiyne.     

The structure and dynamic behaviour in solution of the trihydridodienerhenium complexes (Ph3P)2(η-1,3-diene)ReH3

The structure and fluxionality of the trihydridodiene complexes (Ph₃P)₂(η-1,3-<di-ene)ReH₃ have been studied by NMR spectroscopy (η-1-3-diene = buta-1,3-diene, 2-methylbuta-1,3-diene, 2,3-dimethylbuta-1,3-diene, cyclohexa-1,3-diene, penta-1,3-diene, hexa-1,3-diene and hexa-2,4-diene). Several rearrangement processes have been observed; they are, in order of increasing temperature: (a) ligand interchange; (b) reversible migration of a hydride ligand on to the diene ligand, leading to η-allyl species and, in the case of the cyclohexadiene trihydride, degenerate isomerisation of the cyclohexadiene moiety; and (c), in the case of the pentadiene and hexadiene derivatives, isomerisation of the diene ligand.     

The rearrangement of phosphitohydrazide ligand [(ArO)2P-NPh-NPh-] into iminophosphoranate anion [(PhNP(OAr)2-NPh-] {(ArO)2P = [CH2(BuMeC6H2O)2P]} in coordination sphere of divalent cobalt

The reaction of bromophosphite (ArO)₂PBr {(ArO)₂P = CH₂(6-^tBu-4-Me-C₆H₂O)₂P} with lithium salt of 1,2-diphenylhydrazine gave phosphitohydrazine (ArO)₂P-NPh-NPhH (2) in 64% yield. The last one reacted with Co[N(SiMe₃)₂]₂ to afford cobalt(II) iminophosphoranate (PhNP(OAr)₂-NPh-)₂Co (3), which is the result of isomerisation of the phosphitohydrazide ligand in coordination sphere of divalent cobalt.     

硫杂杯[4]芳烃氧化膦衍生物的合成与晶体结构

合成了部分取代的硫杂杯[4]芳烃氧化膦衍生物, 二(亚甲基二苯基氧化膦)对叔丁基硫杂杯[4]芳烃(化合物1), 培养了化合物的单晶, 用Smart 1000 CCD衍射仪测定了其晶体结构. 结果表明, 1的组成为: C₆₆H₇₀O₆P₂S₄•2CH₃OH, 属三斜晶系, P1空间群, 晶胞参数a＝1.3453(6) nm, b＝1.5289(7) nm, c＝1.7893(9) nm; α＝75.707(9)°, β＝69.131(8)°, γ＝79.734(9)°, Z＝2; V＝3.316(3) nm³, d＝1.215 g/cm³, F(000)＝1288, μ (Mo Kα)＝0.244 mm^－1, R₁＝0.0625, wR₂＝0.1372. 杯芳烃分子采取了锥式构象.     

Molybdenum and tungsten complexes with the heteroallyl-like Ph2P(O)C(S)NR− (R  Me,Ph) as ligand. X-ray structural analysis of Mo(CO)2(PPh3)(Ph2P(O)C(S)NPh)2 · CH2Cl2; A 4 : 3 piano-stool configuration

Ph₂P(O)C(S)N(H)R (R  Me, Ph) reacts with M(CO)₃(η⁵-C₅H₅)Cl (M  Mo, W) in the presence of Et₃N to give M(CO)₂(η⁵-C₅H₅)(Ph₂P(O)C(S)NR). The deprotonated ligand coordinates in a bidentate manner through N and S to give a four-membered ring system. M(CO)₃(PPh₃)₂Cl₂ (M  Mo, W) reacts with Ph₂P(O)C(S)N(H)R (R  Me, Ph) in the presence of Et₃N to give complexes in which the central metal atoms are seven coordinate through two ligands bonded via O and S to form five-membered ring systems, one PPh₃, and two CO groups. The complexes were characterised by elemental analyses, IR, ¹H NMR, and ³¹P NMR spectroscopy, and an X-ray structural analysis of Mo(CO)₂(PPh₃)(Ph₂P(O)C(S)NPh)₂ · CH₂Cl₂.     

2-Phosphinothioyl- and 2-phosphinoylethylcyclopentadienyl zirconium and titanium complexes. Crystal structure of [η5:η1-C5H4CH2CH2P(O)Ph2]TiCl3

The intracomplex conversion of (2-diphenylphosphanoethyl)cyclopentadienyl zirconium and titanium complexes into the corresponding 2-phosphinothioyl and 2-phosphinoyl derivatives, viz., (η⁵-C₅H₅)[η ⁵-C₅H₄CH₂CH₂P(S)Ph₂]ZrCl₂, [η⁵-C₅H₄CH₂CH₂P(S)Ph₂]ZrCl₃, [η⁵:η¹C₅H₄CH₂CH₂P(O)Ph₂]ZrCl₃·THF, and [η⁵:η ¹-C₅H₄CH₂CH₂P(O)Ph₂]TiCl₃ (7), was performed. The NMR spectroscopy data revealed the following order of the coordination ability of the functional groups with respect to the Zr center: Ph₂P=O > Ph₂P > Ph₂P=S. An analogous order was found for the monodentate ligands (Ph₃P=O > Ph₃P > Ph₃P=S) with respect to (η⁵-C₅H₅)ZrCl₃. The molecular structure of complex 7 was established by X-ray diffraction analysis. Coordination of the Ph₂P=O group to the titanium atom was found retained both in the crystalline state and solution.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 116–122, January, 2005.     

Synthesis and characterization of organophosphine/phosphite stabilized silver(I) complexes bearing 2-acetyl-1,3-indandione ligand,crystal structure of [Ph3P·AgC11H7O3]

Six organophosphine/phosphite stabilized silver(I) complexes of 2-acetyl-1,3-indandione (2-AID) of type L_n·AgC₁₁H₇O₃ (L = PPh₃; n = 1, 2a; n = 2, 2b; L = P(OMe)₃; n = 1, 2c; n = 2, 2d; L = P(OEt)₃; n = 1, 2e; n = 2, 2f) have been prepared by reacting of [AgC₁₁H₇O₃], which could be obtained by reacting of 2-AID with AgNO₃, with triphenylphosphine, trimethylphosphite, or triethylphosphite in 1:1–2 M ratio. These complexes were obtained in high yields and characterized by elemental analysis, ¹H, ¹³C{H} NMR, IR spectroscopy, and thermal analysis (TG and DSC), respectively. The molecular structure of 2a has been determined by X-ray single crystal analysis in which the silver atom is in a distorted trigonal geometry.     

Effects of solvent and base on the palladium-catalyzed amination: PdCl2(Ph3P)2/Ph3P-catalyzed selective arylation of primary anilines with aryl bromides

A readily accessible catalytic system, PdCl₂(Ph₃P)₂/Ph₃P, was developed for the selective arylation of primary anilines with aryl bromides. The strong influence of solvents and bases on the catalytic activity was observed. In refluxing o-xylene, triphenylphosphine shows high efficiency for Pd-catalyzed intermolecular amination reactions. By changing the bases, mono- and diarylation of primary amines could be selectively achieved in high yields. Moreover, the catalytic system showed good toleration for the steric hindrance of anilines. A series of N,N,N′,N′-tetraaryl-1,1′-biphenyl-4,4′-diamines, important intermediates of OLED hole transport materials, were synthesized facilely via coupling reactions between 4,4′-diaminobiphenyls and aryl bromides.     

Aminodefluorination of 2-X-pentafluoro-1,4-naphthoquinones (X = NHBu, NEt2, and OMe)

Aminodefluorination of 2-n-butylamino- and 2-diethylaminopentafluoro-1,4-naphthoquinone by alkylamines HNR¹R² (NR¹R² = NHEt, NHⁿBu and NEt₂) occurs at the 6- or 8-position and further, accordingly, at the 8- or at one of the 5- and 6-sites. The isomer ratio changes significantly in favor of a β-replacement product with solvent variation in the sequence: toluene < 1,4-dioxane < DMSO. n-Butylaminodefluorination of 2-methoxypentafluoro-1,4-naphthoquinone gives mixtures of fluorine substitution products both on the benzene and quinone rings.     

Elucidation of inhibitors in the dimerization of acrylonitrile using [RuCl2(DMSO)4/CH3CH2COONa/DMSO/o-benzoylbenzoic acid] as catalyst

A study of inhibitors in the dimerization of acrylonitrile using the novel catalytic system of [RuCl₂(DMSO)₄/CH₃CH₂COONa/DMSO/o-benzoylbenzoic acid] was carried out by examining the effect of reaction products on the catalytic activity. 1,4-Dicyanobuta-1,3-diene (3), one of the linear dimer products of acrylonitrile, inhibited the Ru-catalyzed reaction. Methylthiomethyl o-benzoylbenzoate (8), a by-product which was produced from carboxylic acid and DMSO under the reaction conditions, also acted as an inhibitor.