Copper-catalyzed redox deacylation of isomeric N- and O-benzoylhydroxylamines

Fluorescent, Siderophore-Based Chelators. Design and Synthesis of a Trispyrenyl Trishydroxamate Ligand, an Intramolecular Excimer-Forming Sensing Molecule Which Responds to Iron(III) and Gallium(III) Metal Cations

“…The synthetic route that was followed for the preparation of 5-Bn and 5-Bz is given in Scheme 3. Carbamate alkylation were performed by treatment of 7-Bn and 7-Bz with the halide compound 8 in the presence of NaH (60% in oil) in anhydrous DMF, leading to 6-Bn (71% yield) and 6-Bz (79% yield), respectively. Treatment of 6-Bn with trifluoroacetic acid (in CH 2 Cl 2 ), and of 6-Bz with anhydrous HCl (in dioxane) afforded the corresponding N -deprotected derivatives in almost quantitative yields.…”

“…The purity of all compounds was examined by thin-layer chromatography, using a two-wavelength detection system (365 and 254 nm) and, in the case of the hydroxamate ligands, a visualization method (FeCl 3 ). 1,1,1-Tris((2-(chlorocarbonyl)ethoxy)methyl)ethane, 9 , 1-(chloromethyl)pyrene, 8 , tert -butyl N -(benzyloxy)carbamate, 7-Bn , and tert -butyl- N -(benzoyloxy)carbamate, 7-Bz , were prepared according to published procedures. The following abbreviations have been used: Bn: benzyl; Bz: benzoyl.…”

“…O -Benzoyl- N -( tert -butoxycarbonyl)- N -(1-pyrenyl)hydroxylamine (6-Bz). By the same procedure as above, using 3 g (13 mmol) of tert -butyl- N -(benzoyloxy)carmate, 7-Bz , and 0.52 g of NaH (60% in oil, 13 mmol of NaH) in DMF (80 mL), and 3.5 g (14 mmol) of 1-(chloromethyl)pyrene, 8 , in DMF (50 mL), 6-Bz was obtained as a green-yellow solid (4.5 g, 79%): mp 118−120 °C; R f = 0.72 (CH 2 Cl 2 ). 1 H NMR (60 MHz, CDCl 3 ): 1.5, 5.45, 7.1−8.2 ppm.…”

Palladium(II)‐Catalyzed Dehydrogenative Cross‐Coupling between Two CH Bonds: Unexpected CC Bond Formation

“…Thus, the discovery of an efficient and mild oxidant would be a key to overcoming this substantial hurdle. In the current catalytic system, O ‐benzoyl hydroxylamine itself serves as both the oxidant and the coupling substrate, and piperidine, as the reductive product of piperidin‐1‐yl benzoate, was clearly observed by GC‐MS (for details, see the Supporting Information) 11. In fact, the addition of 2,2,6,6‐tetramethylpiperidin‐1‐yl benzoate (TEMPOBz) resulted in improved yield (Table S1, entry 12 vs. entry 13), whereas the addition of extra oxidants such as copper or silver salts greatly decreased the yield of the heterocoupling products.…”

Computational design of a two-photon excited FRET-based ratiometric fluorescent Cu2+ probe for living cell imaging

“…Hydrazides, hydroxamic acids, and O-acyl hydroxylamines are all known as this kind recognition/reactivity motif with resulting enhanced transacylation reactivity. 38 The approach is depicted in Fig. 1.…”