5-(1-Alkenyl)-1, 3, 4-oxadiazol-2(3H)-one

3-(2-alkenoyl)-thiocarbazic acid O-methyl esters 1 are desulfurated by bromine and the unknown intermediates are transformed by alkali to 5-(1-alkenyl)-1, 3, 4-oxadiazol-2(3H)-ones ( 2 ). This type of oxadiazolone substitution is not realizable by the common ring closure of hydrazides with phosgene due to pyrazolidinone ring closure of unsaturated acids with hydrazine.     

内盐式O-2-(N~3-替加氟)乙基-O-(1-芳硫基-3-铵基)异丙基-硒代磷酯缀合物的合成

六乙基亚磷酰三胺依次与羟乙基替加氟、1-芳硫基甘油及硒反应,制备环甘油硒代磷替加氟缀合物(2);2再与三乙胺或三甲胺反应,完成亲核开环合成了内盐式O-2-(N3-替加氟)乙基-O-(1-芳硫基-3-铵基)异丙基-硒代磷酯缀合物.其结构经1H NMR, 31P NMR及元素分析确证.     

A crossed molecular beam study on the formation of hexenediynyl radicals (H(2)CCCCCCH; C(6)H(3) (X(2)A')) via reactions of tricarbon molecules, C(3)(X(1)Sigma(g)(+)), with allene (H(2)CCCH(2); X(1)A(1)) and methylacetylene (CH(3)CCH; X(1)A(1))

Crossed molecular beams experiments have been utilized to investigate the reaction dynamics between two closed shell species, i.e. the reactions of tricarbon molecules, C(3)(X(1)Sigma(g)(+)), with allene (H(2)CCCH(2); X(1)A(1)), and with methylacetylene (CH(3)CCH; X(1)A(1)). Our investigations indicated that both these reactions featured characteristic threshold energies of 40-50 kJ mol(-1). The reaction dynamics are indirect and suggested the reactions proceeded via an initial addition of the tricarbon molecule to the unsaturated hydrocarbon molecules forming initially cyclic reaction intermediates of the generic formula C(6)H(4). The cyclic intermediates isomerize to yield eventually the acyclic isomers CH(3)CCCCCH (methylacetylene reaction) and H(2)CCCCCCH(2) (allene reaction). Both structures decompose via atomic hydrogen elimination to form the 1-hexene-3,4-diynyl-2 radical (C(6)H(3); H(2)CCCCCCH). Future flame studies utilizing the Advanced Light Source should therefore investigate the existence of 1-hexene-3,4-diynyl-2 radicals in high temperature methylacetylene and allene flames. Since the corresponding C(3)H(3), C(4)H(3), and C(5)H(3) radicals have been identified via their ionization potentials in combustion flames, the existence of the C(6)H(3) isomer 1-hexene-3,4-diynyl-2 can be predicted as well.     

Oxidation of Tricarbonyl (η1 η2-but-3-en-1-yl)iron(0)and Tricarbonyl (η3-allyl)iron(0) Anion Complexes with Dioxygen

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at ?78 °C to give putative tricarbonyl(η¹,η²-but-3-en-1-y1)iron(0) anion complexes and at 25 °C to produce postulated tricarbonyl(η³-allyl)iron(O) anion complexes; trapping of reactive intermediates with dioxygen produced γ,δ-unsaturated acids and allylic alcohols, respectively.     

Rearrangement reactions of the transient lewis acids (CF(3))(3)B and (CF(3))(3)BCF(2): an experimental and theoretical study

Short-lived (CF(3))(3)B and (CF(3))(3)BCF(2) are generated as intermediates by thermal dissociation of (CF(3))(3)BCO and F(-) abstraction from the weak coordinating anion [B(CF(3))(4)](-), respectively. Both Lewis acids cannot be detected because of their instability with respect to rearrangement reactions at the B-C-F moiety. A cascade of 1,2-fluorine shifts to boron followed by perfluoroalkyl group migrations and also difluorocarbene transfer reactions occur. In the gas phase, (CF(3))(3)B rearranges to a mixture of linear perfluoroalkyldifluoroboranes C(n)()F(2)(n)()(+1)BF(2) (n = 2-7), while the respective reactions of (CF(3))(3)BCF(2) result in a mixture of linear (n = 2-4) and branched monoperfluoroalkyldifluoroboranes, e.g., (C(2)F(5))(CF(3))FCBF(2). For comparison, the reactions of [CF(3)BF(3)](-) and [C(2)F(5)BF(3)](-) with AsF(5) are studied, and the products in the case of [CF(3)BF(3)](-) are BF(3) and C(2)F(5)BF(2) whereas in the case of [C(2)F(5)BF(3)](-), C(2)F(5)BF(2) is the sole product. In contrast to reports in the literature, it is found that CF(3)BF(2) is too unstable at room temperature to be detected. The decomposition of (CF(3))(3)BCO in anhydrous HF leads to a mixture of the new conjugate Br?nsted-Lewis acids [H(2)F][(CF(3))(3)BF] and [H(2)F][C(2)F(5)BF(3)]. All reactions are modeled by density functional calculations. The energy barriers of the transition states are low in agreement with the experimental results that (CF(3))(3)B and (CF(3))(3)BCF(2) are short-lived intermediates. Since CF(2) complexes are key intermediates in the rearrangement reactions of (CF(3))(3)B and (CF(3))(3)BCF(2), CF(2) affinities of some perfluoroalkylfluoroboranes are presented. CF(2) affinities are compared to CO and F(-) affinities of selected boranes showing a trend in Lewis acidity, and its influence on the stability of the complexes is discussed. Fluoride ion affinities are calculated for a variety of different fluoroboranes, including perfluorocarboranes, and compared to those of the title compounds.     

Transformation of trans-4-aryl-3-chloro-1-(2-chloroethyl)azetidin-2-ones into 3-aryl-2-(ethylamino)propan-1-ols via intermediate 1-(1-aryl-2-chloro-3-hydroxypropyl)aziridines and trans-2-aryl-3-(hydroxymethyl)aziridines

trans-4-Aryl-3-chloro-1-(2-chloroethyl)azetidin-2-ones, prepared through cyclocondensation of chloroketene and the appropriate imines in a diastereoselective way, were unexpectedly transformed into 3-aryl-2-(ethylamino)propan-1-ols using LiAlH(4) in THF under reflux. A stepwise analysis showed that the initially formed 1-(1-aryl-2-chloro-3-hydroxypropyl)aziridines were converted into trans-2-aryl-3-(hydroxymethyl)aziridines, most probably via N-spiro bis-aziridinium intermediates, which were subsequently prone to undergo ring opening by LiAlH(4) to afford 3-aryl-2-(ethylamino)propan-1-ols.     

Synthesis of 4,4-disubstituted piperidine analogs of (±)-cis-N-[1-(2-hydroxy-2-phenylethyl)-3-methyl-4-piperidyl]-N-phenylpropanamide

Condensation of (±)-1-benzyl-3-methyl-4-piperidone ( 1 ) with aniline followed by trapping of the intermediate imine with cyanide generated a mixture of isomeric nitriles 2A and 2B , the structures of which were established unambiguously by obtaining an X-ray crystal structure on nitrile 2B . Subsequent elaboration of the nitrile intermediates provided analogs of (±)-cis-N-[1-(2-hydroxy-2-phenylethyl)-3-methyl-4-piperidyl]-N-phenylpropanamide having a second substituent (carbomethoxyl, carboethoxyl, methoxymethyl) at the piper-idine 4-position. The conversion of the carboxamide intermediates 3A and 3B to the carboalkoxyl intermediates 5A, 5B and 6A was accomplished utilizing a modified esterification procedure. Proton nmr data are presented for both the final products and the key synthetic intermediates.     

O-(1-芳硒基-3-叠氮基)异丙基- O-2-(N3-替加氟)烷基硫代磷酯的合成与活性

以碘作催化剂, 无水苯为溶剂, 六乙基亚磷酰三胺依次与羟乙基替加氟、1-芳硒基甘油及硫反应, 得中间体硒代环甘油磷脂替加氟缀合物2a～2f. 以无水N,N-二甲基甲酰胺(DMF)作溶剂, 室温下, 叠氮化钠中对2a～2f进行亲核开环, 得到O-(1-芳硒基-3-叠氮基)异丙基-O-2-(N3-替加氟)乙基硫代磷酯. 体外活性测试结果表明, 目标化合物3a～3f 对膀胱癌细胞PGA1抑制作用比替加氟高, 对胃癌细胞BGC-823的抑制作用与替加氟相当.     

1-Ethyl-1,4-dihydro-4-oxo-7-(pyridinyl)-3-quinolinecarboxylic acids. I. Synthesis of 3- and 4-(3-aminophenyl)pyridine intermediates

A series of substituted 3- and 4-(3-aminophenyl)pyridines has been prepared as intermediates for the synthesis of some 1-alkyl-1,4-dihydro-4-oxo-7-pyridinyl-3-quinolinecarboxylic acids. The Hantzsch, Hauser and other pyridine syntheses were used. 4-(3-Aminophenyl)pyridine was prepared via 3-(4-pyridinyl)-2-cyclohexen-1-one using the Semmler-Wolff reaction.     

2-[3-(4-甲氧基苯氧基)丙基]-1,3-二乙酰硫基丙烷的合成

自组装单层膜(SAMs)技术是自20世纪80年代以来快速发展起来的一个新型有机成膜技术,它是通过表面活性剂的头基与基底之间产生化学吸附,在界面上自发形成的有序的单分子层[1].     

Experimental and computational studies on the solvent-controlled cluster isomerism of Ru3(H)(CO)9(NPPh3) and related dynamics

The species Ru3(H)(mu3-NPPh3)(CO)9 occurs in the solid state as two isomers, characterized either by one capping hydride and three CO bridges (1a) or by one bridging hydride and all terminals COs (1b); key intermediates for the formation, fluxionality and solvent-dependent interconversion of the isomers are highlighted through a DFT MO analysis.     

Silica Gel Catalyzed Stereoselective Conversion of Dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates to Dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-2-butenedioates in Solvent-Free Conditions

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 1-hydroxy-2-acetonaphthone leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with conjugate base to produce dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates. Silica gel was found to catalyze conversion of dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates to dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-2-butenedioates in solvent-free conditions at 90°;C in fairly good yields.     

Introduction of a Novel Reaction of Triacetylmethane: One-Pot Synthesis of Dialkyl-2-(3,1-hydroxyethylidene-2,4-pentanedione-3-yl)-3-(triphenylphosphoranylidene)-butanedioate

Protonation of reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylate by 3-(1-hydroxyethylidene)-2,4-pentanedione leads to vinyl phosphonium salts, which undergo Michael addition with the conjugate base of CH-acid to produce the title compounds in high yield.     

The preparation of N-(1H-pyrazol-3-yl)arylamides and 1H-pyrazol-3-amines from polylithiated C(α),N-thiosemicarbazones and C(α),N-semicarbazones

C(α),N-Thiosemicarbazones or C(α),N-semicarbazones were polylithiated with excess lithium diiso-propylamide, and the resulting cyclized intermediates were condensed with aromatic esters to afford N-(1H-pyrazol-3-yl)arylamides. The polylithiated intermediates were also quenched with aqueous acid to give 5-substituted, 1H-pyrazol-3-amines.     

Microwave Induced Conversion of Dialkyl 2-(3-Acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene)Butanedioates to Dialkyl 2-(3-Acetyl-4-hydroxy-1-naphthyl)-2-butenedioates in the Presence of Silica Gel Powder in Solvent-Free Conditions

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 1-hydroxy-2-acetonaphthone leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with conjugate base to produce dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates. Microwave was found to catalyze conversion of dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates to dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-2-butenedioates in the presence of silica gel powder in solvent-free conditions.     

(R)-2-{[4-(3-甲氧基丙氧基)-3-甲基吡啶-2-基]甲基亚硫酰基}- 1H-苯并咪唑的合成

以2,3-二甲基吡啶为起始原料, 经过11步反应, 不对称合成了质子泵抑制剂的关键中间体: (R)-2-{[4-(3-甲氧基丙氧基)-3-甲基吡啶-2-基]甲基亚硫酰基}-1H-苯并咪唑. 研究了用手性高效液相色谱拆分对映体、测定产品光学纯度的方法, 结果表明目标产品的ee值达到99%. 通过IR, UV, MS以及1H NMR分析对重要中间体和目标产品进行了结构鉴定.     

Application of technetium and rhenium carbonyl chemistry to nuclear medicine. Preparation of [NEt4]2[TcCl3(CO)3] from [NBu4][TcO4] and structure of [NEt4][Tc2(μ-Cl)3(CO)6]; structures of the model complexes [NEt4][Re2(μ-OEt)2(μ-OAc)(CO)6] and [ReBr({-CH2S(CH2)2Cl}2)(CO)3]

Transition Metal Chemistry - A detailed investigation of the one-pot synthesis of [NEt4]2[MX3(CO)3] [M=Tc (1a) or Re (1b); X= Cl?, Br?] is presented. The intermediates...     

Modification of 3-substituents in (bacterio)chlorophyll derivatives to prepare 3-ethylated, methylated, and unsubstituted (nickel) pyropheophorbides and their optical properties

Methyl mesopyropheophorbide-a possessing an ethyl group at the 3-position, its 3(1)-demethyl analogue (3-methyl homologue), and its 3(1)-deethyl analogue (3-unsubstituted chlorin) were prepared by modifying naturally occurring (bacterio)chlorophylls bearing 3-vinyl, formyl, acetyl, and 1-hydroxyethyl groups. These synthetic 3-(un)substituted chlorophyll derivatives and their nickel complexes are probable intermediates during degradation of (bacterio)chlorophylls to chemically stable porphyrinoids. The optical properties (visible absorption, circular dichroism, and fluorescence emission) of the catabolic candidates in a solution were measured, and the substitution effect was investigated.     

Vinyl C-F cleavage by Os(H)3Cl(P(i)Pr3)2

Os(H)(3)ClL(2) (L = P(i)Pr(3)) reacts at 20 degrees C with vinyl fluoride in the time of mixing to produce OsHFCl([triple bond]CCH(3))L(2) and H(2). In a competitive reaction, the liberated H(2) converts vinyl fluoride to C(2)H(4) and HF in a reaction catalyzed by Os(H)(3)ClL(2). A variable-temperature NMR study reveals these reactions proceed through the common intermediate OsHCl(H(2))(H(2)C=CHF)L(2), via OsClF(=CHMe)L(2) and OsHCl(H(2))(C(2)H(4))L(2), all of which are detected. DFT(B3PW91) calculations of the potential energy and free energy at 298 K of possible intermediates show the importance of entropy to account for their thermodynamic accessibility. Calculations of unimolecular C-F cleavage of coordinated C(2)H(3)F confirms the high activation energy of this process. Catalysis by HF is thus suggested to account for the fast observed reactions, and scavenging of HF with NEt(3) changes the product to exclusively Os(H)(2)Cl(CCH(3))L(2). The analogous reaction of Os(H)(3)ClL(2) with H(2)C=CF(2) produces exclusively OsHFCl(=CCH(3))L(2) and HF, and the latter is again suggested to catalyze C-F scission via the observed intermediates Os(H)(2)Cl(CF(2)CH(3))L(2) and OsHCl(=CFMe)L(2).     

Michael addition polymerizations of difunctional amines (AA′) and triacrylamides (B3)

Novel hyperbranched poly(amido amine)s containing tertiary amines on the backbones and acryl or secondary amines as the surface groups were successfully synthesized via the Michael addition polymerizations of a triacrylamide [1,3,5‐triacryloylhexahydro‐1,3,5‐triazine (TT)] and a difunctional amine [n‐butylamine (BA)] NMR techniques were used to clarify the structures of hyperbranched polymers and polymerization mechanism. The reactivity of the secondary amine formed in situ was much lower than that of the primary amines in BA. When the feed molar ratio was 1:1 TT/BA, the secondary amine formed in situ was almost kept out of the reaction before the BA (AA′) and TT (B₃) monomers were consumed, and this led to the formation of A′B₂ intermediates containing one secondary amine group and two acryl groups. The self‐polymerization of the A′B₂ intermediates produced hyperbranched polymers bearing acryl as surface groups. For the polymerization with the feed molar ratio of 1:2 TT/BA, A′₂B intermediates containing one acryl group and two secondary amine groups were accumulated until self‐polymerization started; the self‐polymerization of the intermediates formed hyperbranched polymers with secondary amines as their surface groups. Modifications of surface functional groups were studied to form new hyperbranched polymers. The hyperbranched poly(amido amine)s were amorphous. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6226–6242, 2006