RESUMEN
An enantioselective Pd-catalyzed intramolecular dearomative reductive Heck reaction of N-(o-bromoaryl) indole-3-carboxamide is developed. By employing Pd(dba)2/SPINOL-based phosphoramidite as the chiral catalyst and HCO2Na as the hydride source, a series of enantioenriched spiro indolines bearing vicinal stereocenters were afforded in moderate to good yields with excellent enantioselectivities. The reductive Heck reaction of formal tetrasubstituted alkene bearing ß-hydrogens is therefore realized by inhibiting ß-H elimination.
RESUMEN
Herein, we describe a copper-catalyzed intramolecular dearomative amination of indoles via a formal aza-Wacker reaction. This protocol provides an efficient method to access aza-polycyclic indoline molecules bearing exocyclic CîC bonds in moderate to excellent yields in the presence of molecular oxygen as an oxidant. It is worth noting that indolin-3-ones are achieved when employing C3-non-substituted indoles as substrates.
RESUMEN
In the title compound, C18H22O4, the cyclo-hexane and cyclo-hexa-none rings adopt normal chair and half-chair conformations, respectively. The dioxolane ring is almost planar, with an r.m.s. deviation of 0.094â (3)â Å. In the crystal, mol-ecules are connected by O-Hâ¯O hydrogen bonds, forming 21 helical chains along the a-axis direction. The chains are further connected by C-Hâ¯O hydrogen bonds.
RESUMEN
A linear sweep adsorptive stripping voltammetric method (AdS-LSV) for the determination of tobramycin (TOB) has been proposed for the first time. The method is based on the formation of the voltammetrically active iso-butyraldehyde derivative of TOB and the electrochemical behavior of TOB iso-butyraldehyde derivative has been studied. TOB iso-butyraldehyde derivative exhibits a sensitive cathodic peak at -1.40 V (versus SCE) in a medium of B-R buffer (pH 9.8) with a scan rate of 90 mVs(-1) after a preconcentration period of 120 s at -1.10 V (versus SCE). The linear concentration range of application was 6.87 x 10(-9) - 3.44 x 10(-7) mol L(-1) of TOB, with a relative standard deviation of 4.4% (for a level of 1.0 x 10(-7) mol L(-1)) and a detection limit of 3.44 x 10(-9) mol L(-1). The method was applied to the direct determination of TOB in injectable formulations and spiked urine and serum samples.