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Full-Text Articles in Physical Sciences and Mathematics
Organometallic Chemistry Can Simplify The Synthesis Of Important Biologically Active Natural Products, Daniel Becker, P Carter, J. Elliott, R. Lewis
Organometallic Chemistry Can Simplify The Synthesis Of Important Biologically Active Natural Products, Daniel Becker, P Carter, J. Elliott, R. Lewis
Daniel P. Becker
The stereoselectivity of the Pauson--Khand reaction used for the construction of a 6a-carboprostaglandin is described, and a mechanistic hypothesis is proposed to explain the experimentally observed results. A further illustration of the stereoselectivity of the dicobaltoctacarbonyl-mediated cyclization of 1,6-enynes to bicyclo[3.3.0]-octenones is provided by a sequence of transformations that depicts the route to the precursors of pentalenolactone G. Further examples of the synthetic potential of the acetylene-Co$_{2}$(CO)$_{6}$ bimetalloclusters are shown by the synthesis of a vincristine model compound, and a sequence of transformations that provide strong evidence of the intermediacy of a 1,4-diyl (p-benzyne) in the collapse of a Z-diynene …
Stereospecific Dicobalt Octacarbonyl Mediated Enyne Cyclization For The Enantiospecific Synthesis Of A 6a-Carbocycline Analogue, Philip Magnus, Daniel Becker
Stereospecific Dicobalt Octacarbonyl Mediated Enyne Cyclization For The Enantiospecific Synthesis Of A 6a-Carbocycline Analogue, Philip Magnus, Daniel Becker
Daniel P. Becker
D-(+)-Ribonolactone 5 was converted into the butenolide 7 by pyrolysis of the derived ortho ester. Treatment of 7 with trisyl bromide gave the corresponding trisylate 9, which was converted into 10 by using Li,(CH,=CH),CuCN. Exposure of 10 to potassium carbonate in methanol gave epoxide 12, which underwent ring opening when treated with lithium (tri- methylsi1yl)acetylide-BF,.OEt, to give lactone 13. Reduction of lactone 13 with LiAlH, gave diol 18, which was converted into its derived acetonide 19. When 19 was treated with CO,(CO)~/CO/P~,PO, bicyclo[3.3.0]octenone 21 was formed in a highly stereoselective process. Conversion of 21 into the carbocycline analogue 28 was …
New (Nor)Aza-Adamantanes Are Agonists At The Newly Identified Serotonin 5ht4 Receptor And Antagonists At The 5ht3 Receptor, Daniel Flynn, Daniel Becker, Dale Spangler, Roger Nosal
New (Nor)Aza-Adamantanes Are Agonists At The Newly Identified Serotonin 5ht4 Receptor And Antagonists At The 5ht3 Receptor, Daniel Flynn, Daniel Becker, Dale Spangler, Roger Nosal
Daniel P. Becker
New aza(nor)adamantanes 1A, 1B, and 1C are described which exhibit properties of both 5-HT4 agonism and 5-HT3 antagonism. In particular, compound 1C [SC-52491], an azanoradamantane, exhibits an EC50 of 51 nM in a functional model of 5-HT4 agonism and potent antagonism, Ki = 1.2 nM, at the 5-HT3receptor.
Use Of Atom-Transfer Radical Cyclizations As An Efficient Entry Into A New Serotonergic Norazaadamantane, Daniel Flynn, Daniel Becker, Roger Nosal, Daniel Zabrowksi
Use Of Atom-Transfer Radical Cyclizations As An Efficient Entry Into A New Serotonergic Norazaadamantane, Daniel Flynn, Daniel Becker, Roger Nosal, Daniel Zabrowksi
Daniel P. Becker
A route to azanoradamantanes is described which makes use of an atom-transfer radical cyclization to afford 3-azabicyclo[3.3.0]octanes 3A and 3B. Subsequent elaboration of exo-allylamine functionality, followed by cyclization of the endo-hydroxymethyl intermediate 9, affords the new azanoradamantanes 11 and 4. This new azatricyclic system is useful for producing serotonin 5-HT3 antagonists and 5-HT4 agonists.
1,3,4-Trisubstituted Pyrrolidinones As Scaffolds For Construction Of Peptidomimetic Cholecystokinin Antagonists , Daniel Flynn, Clara Villamil, Daniel Becker, Gary Gullikson
1,3,4-Trisubstituted Pyrrolidinones As Scaffolds For Construction Of Peptidomimetic Cholecystokinin Antagonists , Daniel Flynn, Clara Villamil, Daniel Becker, Gary Gullikson
Daniel P. Becker
A new series of cholecystokinin (CCK) antagonists are described which utilizes a new 1,3,4-trisubstituted pyrrolidinone as a scaffold for appending specific amino acid R group mimics (Figure 1). Compound 1A and 1E (SC-50998) exhibit potent nanomolar IC50 values in a CCK-A receptor binding assay. Compound 1E behaves as a competitive antagonist in vitro and is orally active.
Sc-53116: The First Selective Agonist At The Newly Identified Serotonin 5-Ht4 Receptor Subtype, Daniel Flynn, Daniel Zabrowski, Daniel Becker, Roger Nosal
Sc-53116: The First Selective Agonist At The Newly Identified Serotonin 5-Ht4 Receptor Subtype, Daniel Flynn, Daniel Zabrowski, Daniel Becker, Roger Nosal
Daniel P. Becker
No abstract provided.