1500092-75-0Relevant academic research and scientific papers
Multiple absolute stereocontrol in Pd-catalyzed [3+2] cycloaddition of oxazolidinones and trisubstituted alkenes using chiral ammoniumphosphine hybrid ligands
Imagawa, Naomichi,Nagato, Yuya,Ohmatsu, Kohsuke,Ooi, Takashi
, p. 649 - 656 (2016/07/14)
The development of a Pd-catalyzed highly enantio- and diastereoselective [3+2] cycloaddition of 5-vinyloxazolidinones and activated trisubstituted alkenes is described in detail. This protocol for the single-step construction of densely functionalized pyrrolidines with three contiguous stereocenters including vicinal quaternary stereocenters depends on the remarkable ability of phosphine ligands possessing a chiral ammonium ion to promote intermolecular cycloaddition reactions with a precise control of absolute stereochemistry. A series of control experiments show that a chiral ammoniumphosphine hybrid ligand enabled the individual, yet simultaneous stereocontrol of each chiral center in the annulation reaction. The reaction mechanism is also discussed with particular focus on the stereodetermining processes.
Ligand-enabled multiple absolute stereocontrol in metal-catalysed cycloaddition for construction of contiguous all-carbon quaternary stereocentres
Ohmatsu, Kohsuke,Imagawa, Naomichi,Ooi, Takashi
, p. 47 - 51 (2014/01/17)
The development of a general catalytic method for the direct and stereoselective construction of contiguous all-carbon quaternary stereocentres remains a formidable challenge in chemical synthesis. Here, we report a highly enantio- and diastereoselective [3+2] annulation reaction of 5-vinyloxazolidinones and activated trisubstituted alkenes catalysed by a palladium complex bearing a newly devised phosphine ligand with a chiral ammonium salt component, which enables the single-step construction of three contiguous stereocentres, including vicinal all-carbon quaternary stereocentres, in a five-membered heterocyclic framework. This stereoselective cycloaddition protocol relies on the remarkable ability of the chiral ligand to rigorously control the absolute stereochemistry of each chiral centre associated with the multiple bond-forming events, and provides a reliable catalytic process for the asymmetric synthesis of densely functionalized pyrrolidines.
