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23 results on '"Gallagher, Donald J."'

1. Chiral organolithium complexes: the structure of beta-lithiated beta-phenylcarboxamides and the mechanism of asymmetric substitution in the presence of (-)-sparteine

Author

Gallagher, Donald J., Du, Hua, Long, Scott A., and Beak, Peter

Subjects
Amides -- Research, Sparteine -- Research, Chemistry
Abstract

The structure and reactivity of beta-lithiated beta-phenylcarboxamides were studied. NMR spectroscopic studies of two beta-lithiated amides showed that the benzylic lithium was complexed by the nitrogen of the amide. The beta-lithiated N-methyl amide formed a complex with (-)-sparteine which underwent electrophilic substitution to produce enantioenriched products. The beta-lithiated N-isopropyl amide did not form a complex with (-)-sparteine, so there was no asymmetric induction.

Published
1996

2. Synthetic applications of the beta-lithiation of beta-aryl secondary amides: diastereoselective and enantioselective substitutions

Author

Lutz, Gary P., Du, Hua, Gallagher, Donald J., and Beak, Peter

Subjects
Amides -- Research, Substitution reactions -- Research, Biological sciences, Chemistry
Abstract

The regioselective lithiations at the beta-position of beta-aryl secondary amides produce lithiated intermediates that react with many electrophiles to give substituted products. The substituted products formed by the reaction of beta-lithiated amides, containing an alpha-substituent, have high diastereoselectivity. Beta-lithiated N-methylamides give enantioenriched products on electrophilic substitution in the presence of the chiral diamine (-)-sparteine.

Published
1996

3. Chiral organolithium complexes: the effect of ligand structure on the enantioselective deprotonation of Boc-pyrrolidine

Author

Gallagher, Donald J., Wu, Shengde, Nikolic, Nikola A., and Beak, Peter

Subjects
Chemical reactions -- Research, Enantiomers -- Research, Ligands -- Research, Organometallic chemistry -- Research, Biological sciences, Chemistry
Abstract

The feasibility of using s-BuLi/chiral ligand complexes as reagents for the enantioselective conversion of Boc-pyrrolidine to 2-lithio-Boc-pyrrolidine was investigated. To this end, 2-lithio-Boc-pyrrolidine was asymmetrically deprotonated to 2-(trimethylsilyl)-Boc-pyrrolidine and its enantionmeric excess measured. The results showed that diproline-based diamino alcohol and the alpha-methylbenzylamine-derived bispidine ligands to be the most effective among the synthetic ligands. They, however, remain no match for (-)-sparteine.

Published
1995

4. Selectivities in reactions of organolithium reagents with aryl bromides which bear proton-donating groups

Author

Beak, Peter, Musick, Timothy J., Chao Liu, Cooper, Thomas, and Gallagher, Donald J.

Subjects
Organometallic compounds -- Research, Chemical tests and reagents -- Research, Bromides -- Analysis, Lithium -- Analysis, Chemical reactions -- Research, Biological sciences, Chemistry
Abstract

Analyses of bromine lithium exchange reactions for aryl bromides having an acidic protium or deuterium, involved a study of the influence of the structure of the organolithium reagent, the character of the proton donor group with respect to the experimental conditions. A high local concentration of the reagent, which enhances quick reaction, and the exchange reaction inside a previously developed complex, institute the two routes for bromine-lithium exchange reactions.

Published
1993

6. Pathways for stereoinformation transfer: enhanced enantioselectivity via diastereomeric recycling of organolithium/(-)-sparteine complexes

Author

Basu, Amit, Gallagher, Donald J., and Beak, Peter

Subjects
Organometallic compounds -- Research, Organic compounds -- Synthesis, Coordination compounds -- Research, Biological sciences, Chemistry
Abstract

A procedure for determining the energy difference between nonequilibrating diastereomeric complexes of organolithium reagents was evaluated. Lithiation-substitution of N-pivaloyl-o-ethylaniline was conducted in the second step of the process in the presence of (-)-sparteine to give the organolithium intermediate. This reaction provided the second product enriched in the normally less favored enantiomer.

Published
1996

7. Complex-induced proximity effects: evidence for a prelithiation complex and a rate-determining deprotonation in the asymmetric lithiation of Boc-pyrrolidine by an i-PrLi/(-)-sparteine complex

Author

Gallagher, Donald J. and Beak, Peter

Subjects
Complex compounds -- Research, Chemical equilibrium -- Research, Chemical reaction, Rate of -- Research, Sparteine -- Research, Lithium -- Research, Organometallic chemistry -- Research, Biological sciences, Chemistry
Abstract

The kinetics of the asymmetric deprotonation of Boc-pyrrolidine by the i-PrLi/(-)-sparteine complex is described. The results showed that the two compounds form a complex before lithiation in which the equilibrium favors the complex. Deprotonation is step that determines the rate of the asymmetric lithiation process, as shown by the high value for the intermolecular isotope effect.

Published
1995

8. Pilot-Plant Preparation of an αvβ3 Integrin Antagonist. Part 3. Process Research and Development of a Diisopropylcarbodiimide and Catalytic 1-Hydroxybenzotriazole Peptide Coupling

Author

Clark, Jerry D., primary, Anderson, D. Keith, additional, Banaszak, David V., additional, Brown, Derek B., additional, Czyzewski, Ann M., additional, Edeny, Albert D., additional, Forouzi, Puneh S., additional, Gallagher, Donald J., additional, Iskos, V. H., additional, Kleine, H. Peter, additional, Knable, Carl M., additional, Lantz, Melissa K., additional, Lapack, Mark A., additional, Moore, Christine M. V., additional, Muellner, Frank W., additional, Murphy, James B., additional, Orihuela, Carlos A., additional, Pietz, Mark A., additional, Rogers, Thomas E., additional, Ruminski, Peter G., additional, Santhanam, Harish K., additional, Schilke, Tobin C., additional, Shah, Ajit S., additional, Sheikh, Ahmad Y., additional, Weisenburger, Gerald A., additional, and Wise, Bruce E., additional

Published
2009
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9. Efficient Synthesis of (2S,3S)-2-Ethyl-3-methylvaleramide Using (1S,2S)-Pseudoephedrine as a Chiral Auxiliary

Author

Li, Bin-Feng, primary, Hughes, Robert M., additional, Le, Jackie, additional, McGee, Kevin, additional, Gallagher, Donald J., additional, Gross, Raymond S., additional, Provencal, David, additional, Reddy, Jayachandra P., additional, Wang, Peng, additional, Zegelman, Lev, additional, Zhao, Yuxin, additional, and Zook, Scott E., additional

Published
2009
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11. Pilot Plant Preparation of an αvβ3 Integrin Antagonist. Part 1. Process Research and Development of a (S)-β-Amino Acid Ester Intermediate: Synthesis via a Scalable, Diastereoselective Imino-Reformatsky Reaction

Author

Clark, Jerry D., primary, Weisenburger, Gerald A., additional, Anderson, D. Keith, additional, Colson, Pierre-Jean, additional, Edney, Albert D., additional, Gallagher, Donald J., additional, Kleine, H. Peter, additional, Knable, Carl M., additional, Lantz, Melissa K., additional, Moore, Christine M. V., additional, Murphy, James B., additional, Rogers, Thomas E., additional, Ruminski, Peter G., additional, Shah, Ajit S., additional, Storer, Neil, additional, and Wise, Bruce E., additional

Published
2003
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20. Pilot-Plant Preparation of an αvβ3Integrin Antagonist. Part 3. Process Research and Development of a Diisopropylcarbodiimide and Catalytic 1-Hydroxybenzotriazole Peptide Coupling†.

Author

Clark, Jerry D., Anderson, D. Keith, Banaszak, David V., Brown, Derek B., Czyzewski, Ann M., Edeny, Albert D., Forouzi, Puneh S., Gallagher, Donald J., Iskos, V. H., Kleine, H. Peter, Knable, Carl M., Lantz, Melissa K., Lapack, Mark A., Moore, Christine M. V., Muellner, Frank W., Murphy, James B., Orihuela, Carlos A., Pietz, Mark A., Rogers, Thomas E., and Ruminski, Peter G.

Published
2009
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