19357-01-8Relevant academic research and scientific papers
Rhodium-catalyzed asymmetric hydrogenation of olefins with PhthalaPhos, a new class of chiral supramolecular ligands
Pignataro, Luca,Boghi, Michele,Civera, Monica,Carboni, Stefano,Piarulli, Umberto,Gennari, Cesare
supporting information; experimental part, p. 1383 - 1400 (2012/03/27)
A library of 19 binol-derived chiral monophosphites that contain a phthalic acid diamide group (Phthala- Phos) has been designed and synthesized in four steps. These new ligands were screened in the rhodium-catalyzed enantioselective hydrogenation of prochiral dehydroamino esters and enamides. Several members of the library showed excellent enantioselectivity with methyl 2-acetamido acrylate (6 ligands gave >97% ee), methyl (Z)-2- acetamido cinnamate (6 ligands gave >94% ee), and N-(1-phenylvinyl)acetamide (9 ligands gave >95% ee), whilst only a few representatives afforded high enantioselectivities for challenging and industrially relevant substrates N-(3,4-dihydronaphthalen-1- yl)-acetamide (96% ee in one case) and methyl (E)-2-(acetamidomethyl)-3- phenylacrylate (99% ee in one case). In most cases, the new ligands were more active and more stereoselective than their structurally related monodentate phosphites (which are devoid of functional groups that are capable of hydrogen-bonding interactions). Control experiments and kinetic studies were carried out that allowed us to demonstrate that hydrogen-bonding interactions involving the diamide group of the PhthalaPhos ligands strongly contribute to their outstanding catalytic properties. Computational studies carried out on a rhodium precatalyst and on a conceivable intermediate in the hydrogenation catalytic cycle shed some light on the role played by hydrogen bonding, which is likely to act in a substrate-orientation effect.
Organic acids as catalysts for the erosion of polymers
-
, (2008/06/13)
The invention relates to the use of carboxylic acids incorporated as a catalyst in poly(orthoester)s and other acid labile polymers such that upon exposure to aqueous environments the acid catalyzes the erosion of the polymer matrix. The rate of release of a drug substance incorporated into or surrounded by the poly(orthoester) or other acid labile polymer can be controlled in that the drug is released as the polymer is eroded in response to the catalytic action of the acid incorporated therein.
11a-Methano-TXA compounds
-
, (2008/06/13)
The present invention provides novel 11a-methano-TXA compounds and intermediates and processs for their preparation. Further provided are methods for using these novel TXA analogs as inhibitors of thromboxane synthetase, rendering these analogs useful for a variety of pharmacological purposes. These pharmacological uses include anti-inflammatory, anti-thromobitc, and anti-asthma indications.
