Brett M. Showalter

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The sensitivity to decomposition of the nitric oxide (NO) donor ion, 1-[2-(carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (PROLI/NO), complicates direct electrophilic substitution to form useful prodrug derivatives. A modified general synthetic approach involving 1-[2-(hydroxymethyl)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate ion (structure A, above) was(More)
Chemistry Section, Laboratory of ComparatiVe Carcinogenesis, National Cancer Institute at Frederick, Frederick, Maryland 21702, Basic Research Program, SAIC-Frederick, National Cancer Institute at Frederick, Frederick, Maryland 21702, Department of Chemistry, George Mason UniVersity, Fairfax, Virginia 22030, Laboratory of Medicinal Chemistry, National(More)
Diazeniumdiolate ions [R2N-N(O)=N-O-] are of growing interest pharmacologically for their ability to generate up to two molar equivalents of bioactive nitric oxide (NO) spontaneously on protonating the amino nitrogen. Accordingly, their stability increases as the pH is raised. Here we show that the corresponding beta-glucosides [R2N-N(O)=N-O-Glc] decreased(More)
Nitric oxide (NO) has been shown to exhibit significant anti-platelet activity and its release from polymer matrices has been already utilized to increase the biocompatibility of various blood-contacting devices. Herein, details of a new synthetic approach for preparing NO-releasing diazeniumdiolated polyurethanes (PU) are described. The method's utility is(More)
Glycosylated diazeniumdiolates of structure R 2NN(O)NO-R' (R' = a saccharide residue) are potential prodrugs of the nitric oxide (NO)-releasing but acid-sensitive R 2NN(O)NO (-) ion. Moreover, cleaving the acid-stable glycosides under alkaline conditions provides a convenient protecting group strategy for diazeniumdiolate ions. Here, we report comparative(More)
1-Norbornyloxychlorocarbene (1-NorOCCl), 1-bicyclo[2.2.2]octyloxychlorocarbene (1-BcoOCCl), and 1-adamantyloxychlorocarbene (1-AdOCCl) were generated in dichloroethane (DCE) by photolysis of the appropriate diazirines. The exclusive product in each case was the bridgehead alkyl chloride formed by fragmentation of the carbene to [R(+) OC Cl(-)] ion pairs,(More)
New sulfoximine- and phenanthrene-based photochemical precursors to oxynitrenes have been developed. These precursors have been used to examine the chemistry and spectroscopy of oxynitrenes. The first EPR spectra of oxynitrenes are reported and are consistent with their triplet ground states. Additional support for the triplet ground state of oxynitrenes is(More)
[reaction: see text] Iminooxirane 4 has been generated by the reaction of phenylchlorocarbene (2) with phenyl isocyanate (3) and studied by nanosecond time-resolved infrared spectroscopy. Iminooxirane 4 (1830 cm(-1)) isomerizes to alpha-lactam 5 (1880 cm(-1)) at an observed rate of 3 x 10(4) s(-1). Peak assignments were confirmed by a combination of B3LYP(More)
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