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307 results on '"Bates, Robert B."'

3. Dolastatin 11 conformations, analogues and pharmacophore

Author

Ali, Md. Ahad, Bates, Robert B., Crane, Zackary D., Dicus, Christopher W., Gramme, Michelle R., Hamel, Ernest, Marcischak, Jacob, Martinez, David S., McClure, Kelly J., Nakkiew, Pichaya, Pettit, George R., Stessman, Chad C., Sufi, Bilal A., and Yarick, Gayle V.

Published
2005
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4. N,N'-diphenyl-1,4(5)-dimethoxyanthraquinone diimines: 'butterfly' inversion of anthraquinone diimines

Author

Boone, Harold W., Bruck, Michael A., Bates, Robert B., Padias, Anne Buyle, and Hall, H.K., Jr.

Subjects
Dibenzofurans -- Research, Anthraquinones -- Observations, Biological sciences, Chemistry
Abstract

Anthraquinones show that they are sources for HNMR spectroscopy and X-ray single crystal structure properties. The formation of diphenyl can be achieved by a treatment using titanium tetrachloride and 1,4-diazabicyclo octane. The butterfly structure of the X-ray unit is analyzed with HNMR spectroscopy. Details of atomic and molecular structure were also studied.

Published
1995

7. Synthesis and stereochemistry of dolastatin 11

Author

Bates, Robert B., Brusoe, Kennard G., Burns, Jennifer J., Caldera, Sriyani, Cui, Wei, Gangwar, Sanjeev, Gramme, Michelle R., McClure, Kelly J., Rouen, Gregory P., Schadow, Heiko, Stessman, Chad C., Taylor, Stuart R., Vu, Vicky H., Yarick, Gayle V., Zhang, Jianxing, Pettit, George R., and Bontems, Roger

Subjects
Antineoplastic agents -- Research, Cyclic compounds -- Research, High performance liquid chromatography -- Usage, Crystallization -- Usage, Chemistry
Abstract

The first synthesis of dolastatin 11, a potential anticancer agent isolated from the sea hare Dolabella auricularia was carried out using the method previously adapted for the synthesis of didemnins. The synthesis and subsequent purification by HPLC and crystallization led to the identification of seven intermediates and the confirmation of the proposed structure of the protein. It also established the S configuration of the new amino acid Ibu in this natural product, as well as in the closely related dolastatin 12, majusculamide C and 57-normajusculamide.

Published
1997

9. Structure and characterization of flavolipids, a novel class of biosurfactants produced by Flavobacterium sp. strain MTN11

Author

Bodour, Adria A., Guerrero-Barajas, Claudia, Jiorle, Beth V., Malcomson, Mark E., Paull, Amanda K., Somogyi, Arpad, Trinh, Long N., Bates, Robert B., and Maier, Raina M.

Subjects
Natural products, Microbiological synthesis, Surface active agents, Lipids -- Physiological aspects, Lipids -- Synthesis, Biological sciences
Abstract

Research describes the production of flavolipids by a soil bacterium Flavobacterium sp. strain MTN11. Flavolipids range from 584 to 686 in molecular weight and contain a polar moiety made of citric acid and two cadaverine molecules. The critical micelle concentration of 300 milligram per liter and a low surface tension of 26.o mN/m suggest that flavolipids possess strong surfactant activity.

Published
2004

20. Summary

Author

Bates, Robert B., primary and Ogle, Craig A., additional

Published
1983
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25. Dialkylation of ketone dianions

Author

Bates, Robert B. and Taylor, Stuart R.

Subjects
Ketones -- Research, Alkylation -- Analysis, Biological sciences, Chemistry
Abstract

Studies on dialkylations of ketone dianions reveal that alkylation with an alkyl triflate as the second stage electrophile yields the desired alpha-alpha' structured heptanones as reaction products. Dianion dialkylation cyclohexanone with two different alkylating agents, an alkylhalide and an alkyltriflate for the first and second stages, respectively, yields 2,6-dialkylcyclohexanones with Z/E ratio of approximately 2:1. Methanolic sodium methoxide-catalyzed equilibration of the dialkylcyclohexanones changes their Z/E ratios to 4:1.

Published
1994

26. Spectroscopic Characterization of Model Organic Pollutant Interactions with Mineral Oxide Surfaces

Author

Pemberton, Jeanne E., Burke, Michael F., Wysocki, Vicki H., Bates, Robert B., Miller, Walter B., Ringwald, Steven, Pemberton, Jeanne E., Burke, Michael F., Wysocki, Vicki H., Bates, Robert B., Miller, Walter B., and Ringwald, Steven

Abstract

Vibrational spectroscopy is used to elucidate the adsorption mechanisms of model volatile organic pollutants with a variety of mineral oxides. Vapor phase adsorption processes are particularly important in the vadose zone of an aquifer, where void spaces are filled with air and vapor transport is significant. Gaining a better understanding of the interactions occurring at the oxide-air interface is critical in developing or improving remediation strategies. In this work, Raman and infrared spectroscopy are used to obtain molecularly specific information concerning model pollutant-oxide adsorption processes. The choices of pollutants are varied to include several classes of compounds. The interactions of azaarenes, aromatics, chlorinated aromatics, trichloroethylene, and tributyl phosphate are investigated with several mineral types. Pure mineral phases such as silica, alumina, hydrated iron oxide, and montmorillonite clay are used to provide a basis set of interactions, which can be extended to more complex systems in the future. Pollutantoxide interactions, including weak physisorption, hydrogen bonding, Bronsted acid-base, and Lewis acid-base, were identified in this work and varied depending on the specific pollutant-oxide system. This research provides surface adsorption information on environmentally relevant contaminants and the techniques may be utilized to verify the accuracy of pollutant fate and transport models and to improve remediation strategies for such pollutants.

Published
2006

27. alpha-alkoxyacrylic acids from alpha-keto acids

Author

Bates, Robert B. and Caldera, Sriyani

Subjects
Acrylic acid -- Research, Palladium catalysts -- Analysis, Biological sciences, Chemistry
Abstract

Investigations confirm that the methylation and primary alkylation oxygen of dianions offer excellent pathways to alpha-alkoxyacrylic acids, and that they can be synthesized in high concentration from the associated alpha-keto acids. Lochmann's base, (n-butyllithium/potassium tert-butoxide), in THF-hexane was the most suitable base-solvent system for producing dianions.

Published
1993

28. Alkylation of enolates with triflates

Author

Bates, Robert B. and Taylor, Stuart R.

Subjects
Ketones -- Research, Alkylation -- Influence, Gas chromatography -- Usage, Biological sciences, Chemistry
Abstract

The alkylation of enolates from ketones with alkyl triflates in ether or hexane have a high yield (85-98%) and avoid the exchange products occurring when alkyl sulfates are alides and sulfates are employed. The proton exchange to the thermodynamic enolate is more rapid in comparison with alkylation of the kinetic enolate of the intermediate 2-alkyl cyclohexanone. This was determined by potassium hydride in ether employed to generate the potassium enolates cyclohexanone and 2,6-dimethyl cyclohexanone. Reaction 10 had no ethylation products implying that the alkylation of the enolate was more rapid than alkyl exchange between ethyl ether and methyl triflate.

Published
1993

33. Synthesis and biological activities of flavolipids

Author

Ahad, Samiul M., primary, Ange, Alison L., additional, Bates, Robert B., additional, Bell, Bonnie L., additional, Bodour, Adria A., additional, Bourne, Bryan R., additional, Contreras, Cristina G., additional, Goldberg, Emily L., additional, Gunatilaka, A.A. Leslie, additional, King, Sheryl, additional, Lee, Albert K., additional, Low, Rebecca L., additional, Maier, Raina M., additional, Marlor, Kathryn M., additional, Marron, Marilyn T., additional, Scolnik, Ryan C., additional, Streeter, Matthew J., additional, Strelczuk, Malgorzata, additional, Trinh, Long N., additional, Truong, Vu K., additional, Vissering, Sage P., additional, Weick, Megan C., additional, and Williams, Maria T., additional

Published
2010
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36. Synthesis and Antitumor Activity of Heterocycles Related to Carbendazim.

Author

Remers, William A., Iyengar, Bhashyam S., Dorr, Robert T., Wisner, Lee, and Bates, Robert B.

Subjects
CARBENDAZIM, HETEROCYCLIC compounds synthesis, ANTINEOPLASTIC agents, PHARMACEUTICAL chemistry, FUNCTIONAL groups
Abstract

Three types of compounds were synthesized from carbendazim ( 1), a benzimidazole derivative (Scheme [1]). They included a group of esters at N1 prepared by treating carbendazim with isocyanates bearing ester groups ( 2a, 2b, 2c), carboxyalkyl-1,2,3,4-tetrahydro- s-triazino[1,2-a]benzimidazole-2,4-dione esters ( 3a and 3b, 3d and 3c derived from 3a. The antitumor potencies of the N1 esters were in the range of 7 to 40 μM, which compares favorably with carbendazim, but their water solubilities were low. The s-triazine derivatives showed activity against pancreatic tumor cells, and one of them ( 3b) was active in mice, but they were not effective against other tumor types. Treatment of carbendazim with 3-bromopropionyl chloride produced 1-methoxycarbonyl-4-oxo-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole ( 4), which gave 1-(3-aminopropionyl)benzimidazole 2-methylcarbamates, substituted on the amino nitrogen ( 5a, 5b, and 5d), when treated with amines. These products showed some antitumor activity in cell cultures, and an ethoxy derivative ( 5c), obtained by treating 1-methoxycarbonyl-4-oxo-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole with sodium ethoxide, was active in the 67-150 μM range. Some of the new compounds had good water solubility. Carbendazim kills tumor cells by inhibiting tubulin; however, s-triazine 3b, which differs from it in size and functional groups, does not act by this mechanism. [ABSTRACT FROM AUTHOR]

Published
2015
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45. Agatholic acid

Author

Bates, Robert B., primary, Cai, Sheng, additional, Cantor, Ryan S., additional, Carducci, Michael D., additional, Irvine, Anthony K., additional, Jiorle, Beth V., additional, Nakkiew, Pichaya, additional, Setzer, William N., additional, and Trinh, Long N., additional

Published
2002
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49. Saponins from Styrax officinalis

Author

Yayla, Yurdanur, primary, Alankuş-Çalışkan, Özgen, additional, Anıl, Hüseyin, additional, Bates, Robert B, additional, Stessman, Chad C, additional, and Kane, Vinayak V, additional

Published
2002
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