The synthesis of the potent anti-herpes virus agent, E-5(2-bromovinyl)-2′-deoxyuridine and related compounds

The synthesis of $\text{E}$-5(2-bromovinyl)-2′-deoxyuridine in good yield from deoxyuridine $\text{via}$ an intermediate organopalladium derivative is described. The corresponding chloro and iodo compounds have also been made as have the corresponding bromo and iodo 2′-deoxycytidines.     

An altered mechanism of hydrolysis for a metal-complexed phosphate diester

Isotope effects in the nucleophile and in the leaving group were measured to gain information about the mechanism and transition state of the hydrolysis of methyl p-nitrophenyl phosphate complexed to a dinuclear cobalt complex. The complexed diester undergoes hydrolysis about 1011 times faster than the corresponding uncomplexed diester. The kinetic isotope effects indicate that this rate acceleration is accompanied by a change in mechanism. A large inverse 18O isotope effect in the bridging hydroxide nucleophile (0.937 +/- 0.002) suggests that nucleophilic attack occurs before the rate-determining step. Large isotope effects in the nitrophenyl leaving group (18Olg = 1.029 +/- 0.002, 15N = 1.0026 +/- 0.0002) indicate significant fission of the P-O ester bond in the transition state of the rate-determining step. The data indicate that in contrast to uncomplexed diesters, which undergo hydrolysis by a concerted mechanism, the reaction of the complexed diester likely proceeds via an addition-elimination mechanism. The rate-limiting step is expulsion of the p-nitrophenyl leaving group from the intermediate, which proceeds by a late transition state with extensive bond fission to the leaving group. This represents a substantial change in mechanism from the hydrolysis of uncomplexed aryl phosphate diesters.     

Evolution of the interface and metal film morphology in the vapor deposition of Ti on hexadecanethiolate hydrocarbon monolayers on Au

The combination of in situ X-ray photoelectron spectroscopy, infrared reflection spectroscopy, atomic force microscopy, and time-of-flight secondary ion mass spectrometry are used to probe the nature of the evolving interface chemistry and metal morphology arising from Ti vapor deposition onto the surface of a CH(3)(CH(2))(15)S/Au{111} self-assembled monolayer (SAM) at ambient temperature. The results show that for a deposition rate of approximately 0.15 Ti atom.nm(-2).s(-1) a highly nonuniform Ti overlayer is produced via a process in which a large fraction of impinging Ti atoms do not stick to the bare SAM surface. The adsorbed atoms form isolated Ti clusters and react with CH(3) groups to form carbide products at the cluster-SAM interfaces. Further growth of Ti clusters appears to be concentrated at these scattered reaction centers. The SAM molecules in the local vicinity are subsequently degraded to inorganic products, progressing deeper into the monolayer as the deposition proceeds to give an inorganic/organic nanocomposite. A continuous overlayer does not form until metal coverage approaches approximately 50 Ti atoms per SAM molecule. These data indicate that for applications such as molecular device contacts the use of Ti may be highly problematic, suffering from both a highly nonuniform contact area and the presence of extensive inorganic products such as nonstoichiometric carbides and hydrides.     

Amide bond formation using an air-stable source of AlMe3

Synthesis of amides from coupling esters with a range of primary amines can be conveniently achieved in moderate to excellent yields (69-99%) using an air-stable adduct of trimethylaluminium (AlMe₃)₂·DABCO (DABCO is 1,4-diazobicyclo[2.2.2]octane), referred to as DABAL-Me₃. Reactions can be run without requiring the exclusion of atmospheric oxygen or the drying of solvents.     

Palladium salicylaldimine complexes containing boronate esters

Reactions of salicylaldehydes with boronate ester derivatives of aniline have been examined. Addition of these Schiff base ligands to palladium acetate or Na₂PdCl₄ afforded novel boron-containing trans-bis(N-arylsalicylaldiminato) palladium complexes.Condensation of salicylaldehyde (2-HOC₆H₄C(O)H) with H₂NC₆H₄Bpin (pin=1,2-O₂C₂Me₄) afforded the boron-containing Schiff bases, 2-HOC₆H₄C(H)=NC₆H₄Bpin (1–3a). Similar reactivity with 2-hydroxy-5-nitrobenzaldehyde and 2-hydroxy-1-naphthaldehyde gave the corresponding Schiff bases (1-3b) and (1-3c), respectively. Reaction of Schiff bases (2) and (3) with palladium acetate or Na₂PdCl₄ afforded complexes of the type PdL₂ (4,5), where L=deprotonated Schiff base. The molecular structure of the nitro-salicylaldehyde 4-Bpin palladium complex (5b) was characterized by an X-ray diffraction study. All new palladium compounds have been characterized fully and tested for their antifungal activity against Aspergillus niger and Aspergillus flavus.     

Rapid separation of phenylthiohydantoin amino acids: ambient pressure ion-mobility mass spectrometry (IMMS)

An electrospray ionization (ESI) ambient pressure ion-mobility spectrometer (APIMS) interfaced to an orthogonal reflector time-of-flight mass spectrometer (TOFMS) was evaluated for the first time as a detector for the identification of phenylthiohydantoin (PTH)-derivatized amino acids, the final products in the Edman sequencing process of peptides and proteins. The drift and flight times of the twenty common PTH amino acids were characterized by a well-defined 2-D mobility/mass spectral pattern. The combination of mobility/mass modes of analysis gave rise to a unique trend-line formation for the series of PTH amino acids. In addition, each PTH amino acid had a unique reduced mobility constant K(o), thus enabling the differentiation of all the amino acid derivatives including the PTH-leucine and PTH-isoleucine isomers. More importantly it was shown that it was possible to resolve a complete reference mixture of PTH amino acids in a single experimental run in less than 1 min. Detection limits for the PTH amino acids were found to range from 1.04 to 3.52 ng; indicating that the limits of detection were less than 17.0 pmol for all of the PTH amino acids.     

Synthesis,crystal structure and luminescent property of a novel H<Subscript>2</Subscript>O-bridged cobalt(II) polymer with one-dimensional chain structure

The coordination compound [Co(C₁₀H₇COO)₂(H₂O)₃]_2n · 4nH₂O was prepared by the reaction of 1-naphthoic acid and cobalt(II) acetate tetrahydrate in basic solution, and was fully characterized by X-ray diffraction, element analysis, FTIR, TG-DTA and luminescent spectra. In the crystal the six-coordinated Co(II) centers are linked into one-dimensional zigzag chains by water molecules, which are further assembled into a two-dimensional network through weak inter-chain C–H···π interactions. The solid complex exhibits favorable fluorescent properties similar to those of free ligand at room temperature, which can be assigned to the intraligand electronic transfer.     

Conversion of 3-benzoyl-1-methyl-4-phenyl-γ-piperidol by arylamines and arylhydrazines. Synthesis of 3-arylamino-1-oxo-1-phenylpropanes and 1,3-diarylpyrazoles and their fragmentation under electron impact

It has been established that on heating, 3-benzoyl-4-hydroxy-1-methyl-4-phenylpiperidine is ring-opened in the presence of arylamines by a type of retroaldol reaction, with subsequent transamination of the intermediate Mannich base and the formation of 3-arylamino-1-oxo-1-phenylpropanes. When using arylhydrazines this γ-piperidol is recyclized with the formation of 1,3-diarylpyrazoles and their 4,5-dihydro derivatives. The mass spectral behavior of a series of 3-arylamino-substituted 1-phenylpropanones has been studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1486–1495, October, 2007.     

The Effect of Alkane Chain Length on the Liquid–Liquid Critical Temperatures of Oligostyrene/Linear-Alkane Mixtures

Summary. Upper critical solution temperatures (UCSTs) for liquid–liquid demixing in a set of mixtures of linear alkanes (pentane (N ₁=5) to pentacontane (N ₁=50)) with an oligostyrene (1241amu, N ₂=12) are reported. We find strong correlation between the Hildebrand solubility parameters of the alkanes and the UCST. Correlations are developed which enable predictions concerning the miscibility of mixtures of compounds with longer chains.     

Isomerization of 2,5-divinyltetrahydropyran and acid-catalyzed rearrangements of isomeric novel dihydropyrans

2,5-Divinyltetrahydropyran (1) can be isomerized using a ruthenium trichloride- triphenylphosphine catalyst to give 3,4-dihydro-3-vinyl-6-ethyl-2H-pyran (2) and 3,4-dihydro-3- ethylidene-6-ethyl-2H-pyran (3). These products give a variety of rearranged products on treatment with acid. The course of the reactions can be controlled by reaction conditions to give 4-ethyltoluene (5) or 3-hydroxymethyl-1-octen-6-one (4) from 2, and 3,4-dihydro-2-methyl-3-methylene-(6-ethyl-2H- pyran (7), 2,3,4-trimethyl-2-cyclohexen-1-one (8), or 3-hydroxymethyl-2-octen-6-one (6) from 3. All of these products (4–8) can be explained as arising by the initial opening of the dihydropyran to generate an unsaturated hydroxy ketone which then cyclizes to carbocyclic products.