Steric and electronic effects in the enantioselective hydrogenation of activated ketones on platinum: Directing effect of ester group
作者:S DIEZI、S REIMANN、N BONALUMI、T MALLAT、A BAIKER
DOI:10.1016/j.jcat.2006.02.001
日期:2006.4.25
of the steric bulkiness of the α -ketoester. None of the mechanistic models developed for ketonehydrogenation on Pt are conform to the observations. Only additional steric effects in the modifiers and replacement of toluene by acetic acid as a reaction medium enhanced the sensitivity of the catalyst system to steric effects in the substrates (ee=0–94%ee=0–94%). An important mechanistic consequence
Asymmetric Vinylogous Aldol Reaction of<i>α</i>-ketoesters with 3-alkylidene oxindoles
作者:Krishna Kumar、Manish K. Jaiswal、Ravi P. Singh
DOI:10.1002/adsc.201700758
日期:2017.12.11
An efficient enantioselective vinylogousaldolreaction of 3-alkylidene oxindoles with α-ketoesters by a bifunctional thiourea catalyst derived from cinchona alkaloid has been disclosed here. The simultaneous H-bond directing dual activation of vinylogous nucleophile and electrophile afforded high yield (upto 92%) while obtaining excellent stereocontrol (upto 99% ee).
Enantioselective addition of nitromethane to α-keto esters catalyzed by copper(<scp>ii</scp>)–iminopyridine complexes
作者:Gonzalo Blay、Victor Hernández-Olmos、José R. Pedro
DOI:10.1039/b716446g
日期:——
The coppercomplex of a chiral iminopyridine easily prepared from (R)-(-)-fenchone and picolylamine catalyzes the enantioselective Henry (nitroaldol) reaction between nitromethane and alpha-keto esters. Good yields and modest to good enantioselectivities are obtained for a wide range of alpha-keto esters, bearing aromatic, alkyl or alkenyl groups attached to the ketone carbonyl group.
The synthesis and structure–activity relationships of 1,3-diaryl 1,2,4-(4 H )-triazol-5-ones: A new class of calcium-dependent, large conductance, potassium (maxi-k) channel opener targeted for urge urinary incontinence
作者:Piyasena Hewawasam、Matthew Erway、George Thalody、Harvey Weiner、Christopher G Boissard、Valentin K Gribkoff、Nicholas A Meanwell、Nicholas Lodge、John E Starrett, Jr
DOI:10.1016/s0960-894x(02)00099-9
日期:2002.4
A series of 1,3-diaryl 1,2,4-(4H)-triazol-5-ones was prepared and shown by electrophysiological analysis to activate a cloned maxi-K channel mSlo (or hSlo) expressed in Xenopus laevis oocytes. The effects of these structurally novel maxi-K channel openers on bladder contractile function were studied in vitro using isolated rat bladder strips pre-contracted with carbachol. Several 1,3-diaryl l,2,4-(4H)-triazol-5-one derivatives were found to be potent smooth muscle relaxants but this activity did not completely correlate with maxi-K channel opening. (C) 2002 Elsevier Science Ltd. All rights reserved.
Synthesis and pharmacological characterization of constrained analogues of Vestipitant as in vitro potent and orally active NK1 receptor antagonists
作者:Fabio M. Sabbatini、Romano Di Fabio、Cristiana Griffante、Giorgio Pentassuglia、Laura Zonzini、Sergio Melotto、Giuseppe Alvaro、Anna M. Capelli、Lara Pippo、Elisabetta Perdona’、Yves St. Denis、Silvano Costa、Mauro Corsi
DOI:10.1016/j.bmcl.2009.11.078
日期:2010.1
A focused exploration targeting conformationally restricted analogues of Vestipitant, resulted in the discovery of novel, in vitro potent NK1 antagonists. In particular, two of the compounds reported exhibited a good pharmacokinetic (PK) profile and produced anxiolytic-like effects in the gerbil foot tapping (GFT) in vivo model. (C) 2009 Elsevier Ltd. All rights reserved.