J
Joseph D. Armstrong
Researcher at Merck & Co.
Publications - 67
Citations - 2098
Joseph D. Armstrong is an academic researcher from Merck & Co.. The author has contributed to research in topics: Catalysis & Enantioselective synthesis. The author has an hindex of 24, co-authored 67 publications receiving 2012 citations. Previous affiliations of Joseph D. Armstrong include Sirna Therapeutics & United States Military Academy.
Papers
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Journal ArticleDOI
Highly Efficient Asymmetric Synthesis of Sitagliptin
Karl B. Hansen,Yi Hsiao,Feng Xu,Nelo R. Rivera,Andrew M. Clausen,Michele Kubryk,Shane W. Krska,Thorsten Rosner,Bryon Simmons,Jaume Balsells,Nori Ikemoto,Yongkui Sun,Felix Spindler,Christophe Malan,Edward J. J. Grabowski,Joseph D. Armstrong +15 more
TL;DR: This environmentally friendly, 'green' synthesis significantly reduces the total waste generated per kilogram of sitagliptin produced in comparison with the first-generation route and completely eliminates aqueous waste streams.
Journal ArticleDOI
Stereochemical control in the ester enolate Claisen rearrangement. 1. Stereoselectivity in silyl ketene acetal formation
Journal ArticleDOI
Highly Efficient Synthesis of β-Amino Acid Derivatives via Asymmetric Hydrogenation of Unprotected Enamines
Yi Hsiao,Nelo R. Rivera,Thorsten Rosner,Shane W. Krska,Eugenia Njolito,Fang Wang,Yongkui Sun,Joseph D. Armstrong,Edward J. J. Grabowski,Richard D. Tillyer,Felix Spindler,Christophe Malan +11 more
TL;DR: A direct asymmetric hydrogenation of unprotected enamino esters and amides is described, catalyzed by Rh complexes with Josiphos-type chiral ligands, which gives beta-amino amides in high yield and high ee.
Journal ArticleDOI
First Generation Process for the Preparation of the DPP-IV Inhibitor Sitagliptin
Karl B. Hansen,Jaume Balsells,Spencer D. Dreher,Yi Hsiao,Michele Kubryk,Michael Palucki,Nelo R. Rivera,Dietrich Steinhuebel,Joseph D. Armstrong,David Askin,Edward J. J. Grabowski +10 more
TL;DR: In this paper, a new synthesis of sitagliptin (MK-0431), a DPP-IV inhibitor and potential new treatment for type II diabetes, suitable for the preparation of multi-kilogram quantities is presented.
Patent
Novel crystalline forms of a phosphoric acid salt of a dipeptidyl peptidase-IV inhibitor
Robert M. Wenslow,Joseph D. Armstrong,Alex M. Chen,Stephen Cypes,Russell R. Ferlita,Karl B. Hansen,Christopher M. Lindemann,Evangelia Spartalis +7 more
TL;DR: In this article, anhydrate polymorphs of the dihydrogenphosphate salt of (2R)-4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-α]pyrazin-7(8H)-yl]-1-(2, 4,5-triflorophenyl)butan-2-amine as well as a crystalline desolvated polymorph and their use for the preparation of the