Synthesis of substituted 5-diethoxymethyl-5-ethyloxazolidines

Mixtures of stereoisomeric 2-diethoxymethyl-5-ethyloxazolidines with one of the stereoisomeric forms predominating were obtained by the reaction of 2-ethyl-2-formyloxirane diethyl acetal with alkyl-substituted Schiff bases in ethanol solution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, 985–988, July, 1987.     

The Transit Route Arc-Node Service Maximization problem

This article presents a new method for determining optimal transit routes. The Transit Route Arc-Node Service Maximization model is a mathematical model that maximizes the service value of a route, rather than minimizing cost. Cost (distance) is considered as a budget constraint on the extent of the route. The mathematical formulation modifies and exploits the structure of linear programming problems designed for the traveling salesman problem. An innovative divide-and-conquer solution procedure is presented that not only makes the transit routing problem tractable, but also provides a range of high-quality alternate routes for consideration, some of which have substantially varying geometries. Variant formulations are provided for several common transit route types. The model is tested through its application to an existing street network in Richardson, TX. Optimal numeric results are obtained for several problem instances, and these results demonstrate that increased route cost is not correlated with increased service provision.     

In vitro anticancer activity and biologically relevant metabolization of organometallic ruthenium complexes with carbohydrate-based ligands

The synthesis and in vitro anticancer activity of dihalogenido(eta6-p-cymene)(3,5,6-bicyclophosphite-alpha-D-glucofuranoside)ruthenium(II) complexes are described. The compounds were characterized by NMR spectroscopy and ESI mass spectrometry, and the molecular structures of dichlorido-, dibromido- and diiodido(eta6-p-cymene)(3,5,6-bicyclophosphite-1,2-O-isopropylidene-alpha-D-glucofuranoside)ruthenium(II) were determined by X-ray diffraction analysis. The complexes were shown to undergo aquation of the first halido ligand in aqueous solution, followed by hydrolysis of a P--O bond of the phosphite ligand, and finally formation of dinuclear species. The hydrolysis mechanism was confirmed by DFT calculations. The aquation of the complexes was markedly suppressed in 100 mM NaCl solution, and notably only very slow hydrolysis of the P--O bond was observed. The complexes showed affinity towards albumin and transferrin and monoadduct formation with 9-ethylguanine. In vitro studies revealed that the 3,5,6-bicyclophosphite-1,2-O-cyclohexylidene-alpha-D-glucofuranoside complex is the most cytotoxic compound in human cancer cell lines (IC50 values from 30 to 300 microM depending on the cell line).     

Copper-catalyzed synthesis of enantioenriched tetraarylethanes

Herein we report the asymmetric synthesis of 1,2-dipyridyl-1,2-diarylethanes via an unusual Cu(I)-catalyzed dimerization reaction. Subjection of a variety of enantioenriched substituted 2-pyridyl alcohols to a one-pot protocol generates the desired products in good yields and diastereoselectivities and with ee's up to >99%.     

Novel copolymers of styrene. 4. Halogen ring-substituted propyl 2-cyano-3-phenyl-2-propenoates

Novel trisubstituted ethylenes, halogen ring-substituted propyl 2-cyano-3-phenyl-2-propenoates, RPhCH ? C(CN)CO₂C₃H₇ (where R is 2-Br, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 2-F, 3-F, 4-F were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and propyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C-NMR. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (0.9–4.7% wt.), which then decomposed in the 500–800°C range.     

Condensation of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester and decarboxylation of the reaction products obtained

-(1-Ethoxyvinyl)- and -(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactones were obtained by the reaction of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester. Decarboxylation of the -(1-ethoxyvinyl)--ethoxycarbonyl-butyrolactones in DMSO leads to -(1-ethoxyvinyl)--butyrolactones, the hydrolysis of which gives -acetyl-butyrolactones. Ethyl trans-3-acetyl-3-pentenoate was obtained by decarboxylation of -methyl--(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactone in DMSO.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 22–25, January, 1992.     

Heterocyclization of acryloyloxiranes to 3-hydroxy-4-piperidinones and 2-(α-hydroxyalkyl)-3-pyrrolidinones in the reaction with methylamine

3-Hydroxy-4-piperidinones and 2-(-hydroxyalkyl)-3-pyrrolidinones were obtained by the reaction of acryloyloxiranes with methylamine. It is shown that the regiospecificity of the heterocyclization of the products of addition of methylamine to the double bond of the acryloyloxirane is determined by the substituents attached to the - and -carbon atoms of the epoxide ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1344–1350, October, 1988. Original article submitted March 30, 1987.     

Systematic evaluation of new chiral stationary phases for supercritical fluid chromatography using a standard racemate library

A systematic approach to the evaluation of new chiral stationary phases (CSPs) for supercritical fluid chromatography (SFC) using a standard library of racemic analytes is described. A standard library of racemic analytes representing a variety of functional group classes was assembled from a mixture of proprietary and commercial compounds. The library is dispensed and stored in a convenient 96-well microplate format to facilitate ease of use, and to minimize the amount of analyte required for analysis. Automated SFC screening was performed on both established CSPs in common use, as well as a group of six recently commercialized CSPs. Screening results were archived in a structure-searchable database that allows convenient comparison of performance data to determine which CSPs shows the best performance.