Chemo- and Site-Selective Alkyl and Aryl Azide Reductions with Heterogeneous Nanoparticle Catalysts
作者:Venkatareddy Udumula、S. Hadi Nazari、Scott R. Burt、Madher N. Alfindee、David J. Michaelis
DOI:10.1021/acscatal.6b01217
日期:2016.7.1
to generating new leads for drug discovery. Herein, we show that heterogeneous nanoparticle catalysts enable site-selective monoreduction of polyazide substrates for the generation of aminoglycoside antibiotic derivatives. The nanoparticle catalysts are highly chemoselective for reduction of alkyl and aryl azides under mild conditions and in the presence of a variety of easily reduced functional groups
Catalytic Staudinger Reduction at Room Temperature
作者:Danny C. Lenstra、Joris J. Wolf、Jasmin Mecinović
DOI:10.1021/acs.joc.9b00831
日期:2019.5.17
catalytic Staudingerreduction at room temperature that enables the preparation of a structurally diverse set of amines from azides in excellent yields. The reaction is based on the use of catalytic amounts of triphenylphosphine as a phosphine source and diphenyldisiloxane as a reducing agent. Our catalytic Staudingerreduction exhibits a high chemoselectivity, as exemplified by reduction of azides
Weak Interactions Dominating the Supramolecular Self-Assembly in a Salt: A Designed Single-Crystal-to-Single-Crystal Topochemical Polymerization of a Terminal Aryldiacetylene
作者:Zhong Li、Frank W. Fowler、Joseph W. Lauher
DOI:10.1021/ja806663h
日期:2009.1.21
Single-crystal-to-single-crystal (SCSC) topochemical polymerizations of diacetylenes can yield nearly defect-free conjugated polymer crystals unattainable by other methods. Aryl-substituted diacetylenes with their potentially greater conjugation have been targeted for years, but until now no one has reported a SCSC polymerization of any aryl-substituted diacetylene. This is presumably due to the rigidity of such diaryl-substituted monomers as well as the lack of control over the supramolecular structure. To address this problem, the polymerization of a terminal phenyldiacetylene was targeted. It was assumed that a terminal diacetylene should demonstrate greater flexibility in the solid state. To establish the necessary (similar to 4.9 angstrom) repeat distance, commensurate with the repeat distance in the polymer, a host-guest system was designed. The chosen diacetylene guest, the amine DABzNH(2), was to be crystallized with the oxalamide dicarboxylic acid host, H(2)og. The plan required a segregation of the hydrogen bonds, amide-amide hydrogen bonds to establish the 4.9 angstrom spacing, and the carboxylate to ammonium ion hydrogen bonds to organize the guest. Prior to carrying out the diacetylene synthesis a series of model salts were studied. Consistent with the hydrophobic effect it was found that amines with large "greasy" substituents assembled according to the design. Once the model studies established that weak interactions could dominate the supramolecular structure of a salt, the actual design was put to the test. The targeted guest, DABzNH(2), was synthesized and crystals of the host-guest salt (DABzNH(3))(2)og were prepared. The resulting crystal structure was in complete accordance with the design. A SCSC polymerization was achieved by a slow annealing treatment lasting about three months. The crystal structure of the resulting polymer not only confirmed the first example of a poly (aryldiacetylene) single crystal, it also revealed an unexpected reaction pathway that shows a major movement involving the rigid aromatic substituent.
Design and Synthesis of Dual-Action Inhibitors Targeting Histone Deacetylases and 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase for Cancer Treatment
A series of dual-action compounds were designed to target histone deacetylase (HDAC) and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) by having a hydroxamate group essential for chelation with the zinc ion in the active site of HDAC and the key structural elements of statin for binding with both proteins. In our study, the statin hydroxamic acids prepared by a fused strategy are most promising in cancer treatments. These compounds showed potent inhibitory activities against HDACs and HMGR with IC50 values in the nanomolar range. These compounds also effectively reduced the HMGR activity as well as promoted the acetylations of histone and tubulin in cancer cells, but were not toxic to normal cells.