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Highly Efficient Procedure (highly + efficient_procedure)
Selected AbstractsRu(IV)-Catalyzed Isomerization of Allylamines in Water: A Highly Efficient Procedure for the Deprotection of N-Allylic Amines.CHEMINFORM, Issue 51 2005Victorio Cadierno Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Highly Efficient Procedure for Regeneration of Carbonyl Groups from Their Corresponding Oxathioacetals and Dithioacetals Using Sodium Nitrite and Acetyl Chloride in Dichloromethane.CHEMINFORM, Issue 23 2003Abu T. Khan Abstract For Abstract see ChemInform Abstract in Full Text. [source] Reduction of Alkyl Halides by Triethylsilane Based on a Cationic Iridium Bis(phosphinite) Pincer Catalyst: Scope, Selectivity and MechanismADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Jian Yang Abstract A highly efficient procedure for the reduction of a broad range of alkyl halides by triethylsilane based on a cationic iridium bis(phosphinite) pincer catalyst has been discovered and developed. This reduction chemistry is chemoselective and has unique selectivities compared with conventional radical-based processes and the aluminum trichloride/triethylsilane (AlCl3/Et3SiH) and triphenylmethyl tetrakis[pentafluorophenyl]borate/triethylsilane {[Ph3C] [B(C6F5)4]/Et3SiH} systems. Reductions use three equivalents of triethylsilane relative to the halide and can be carried out with very low catalyst loadings and in a solvent-free manner, which may provide an environmentally attractive and safe alternative to many currently practiced methods for reduction of alkyl halides. Mechanistic studies reveal a unique catalytic cycle. The cationic iridium hydride 2,6-bis[di-(tert -butyl)phosphinyloxy)phenyl(hydrido)iridium, (POCOP)IrH+ {POCOP= 2,6-[OP(t- Bu)2]2C6H3} binds and activates the silane. This complex serves as a potent silylating reagent to generate silyl halonium ions, Et3SiXR+, which are reduced by the neutral iridium dihydride to yield alkane product and regenerate the cationic (POCOP)IrH+, thus closing the catalytic cycle. All key intermediates have been identified by in situ NMR monitoring and kinetic studies have been completed. An application of this reduction system to the catalytic hydrodehalogenation of a metal chloride complex is also described. [source] Percutaneous nephrolithotomy with ultrasonography-guided renal access: experience from over 300 casesBJU INTERNATIONAL, Issue 6 2005Mahmoud Osman OBJECTIVE To report our experience with over 300 patients treated with percutaneous nephrolithotomy (PNL), for although PNL was established as a treatment in the 1970s, its use diminished with the introduction of extracorporeal shockwave lithotripsy (ESWL); clinical experience with ESWL showed its limitations, and the role of PNL for treating urolithiasis was redefined, which with improvements in instruments and lithotripsy technology has expanded the capability of percutaneous stone disintegration. PATIENTS AND METHODS The study included 315 patients (156 males, 159 females, aged 13,85 years) treated with PNL in our department between 1987 and 2002. The mean (range) stone diameter was 27 (7,52) mm. The kidney was punctured under ultrasonography guidance via a lower-pole calyx whenever possible. The working channel was dilated using an Alken dilator under X-ray control. If necessary, a flexible renoscope was used. Ultrasonic, pneumatic and laser probes were used for lithotripsy. RESULTS Four weeks after treatment the total stone-free rate was 96.5%; 45.7% of all patients were primarily stone-free, 21.3% had clinically insignificant residual stones that passed spontaneously within 4 weeks after PNL, and 33% of the patients needed auxiliary measures (a second PNL, ESWL, ureterorenoscopy). Overall, the early complication rate was 50.8%, the most common complications being transient fever (27.6%), clinically insignificant bleeding (7.6%) or both (3.2%); 3.5% of the patients developed urinary tract infections (with no signs of urosepsis), 3.2% had renal colic and 2.9% upper urinary tract obstruction. One patient (0.3%) developed acute pancreatitis after PNL; one died from urosepsis and one needed selective angiographic embolization of the punctured kidney due to bleeding. No patient required transfusions and there were no injuries to neighbouring organs. CONCLUSIONS These results show that PNL causes no significant blood loss or major complications in almost all patients. Two aspects may especially reduce the potential complications: ultrasonography-guided renal puncture and using PNL in an experienced centre. PNL is a highly efficient procedure that provides fast and safe stone removal. [source] | ||||||||||