1253889-39-2Relevant academic research and scientific papers
Enantioselective synthesis of 1-vinyltetrahydroisoquinolines through palladium-catalysed intramolecular allylic amidation with chiral PhthalaPhos ligands
Pignataro, Luca,Marelli, Enrico,Gennari, Cesare,Ferraccioli, Raffaella
, p. 844 - 850 (2014/06/23)
The PhthalaPhos ligands, chiral BINOL monophosphites endowed with a phthalamide group, have been screened in the synthesis of 1- vinyltetrahydroisoquinolines by intramolecular palladium-catalysed asymmetric allylic amidation (AAA) of achiral tosylamidocarbonates. Identification of the best ligand followed by optimisation of the reaction conditions allowed the desired product to be obtained with up to 83% ee. Remarkably, the reaction is stereoconvergent, affording the same enantiomer of the desired product regardless of the geometry of the allylic carbonate's double bond, which allows, in principle, the use of E/Z mixtures.
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.
Phthalaphos: Chiral supramolecular ligands for enantioselective rhodium-catalyzed hydrogenation reactions
Pignataro, Luca,Carboni, Stefano,Civera, Monica,Colombo, Raffaele,Piarulli, Umberto,Gennari, Cesare
supporting information; experimental part, p. 6633 - 6637 (2010/10/21)
Interligand hydrogen bonding of chiral monodentate phosphite ligands bearing H-bond donor and acceptor groups leads to formation of supramolecular bidentate ligands, rhodium complexes of which (see picture) afford excellent enantiomeric excesses in catalyzed hydrogenation of classical benchmark and industrially relevant substrates. cod=1,5-cyclooctadiene.
