1099856-41-3Relevant academic research and scientific papers
Controlling Enantioselectivity and Diastereoselectivity in Radical Cascade Cyclization for Construction of Bicyclic Structures
Lee, Wan-Chen Cindy,Mckillop, Alexander M.,Wang, Duo-Sheng,Zhang, Congzhe,Zhang, X. Peter
supporting information, p. 11130 - 11140 (2021/07/31)
Radical cascade cyclization reactions are highly attractive synthetic tools for the construction of polycyclic molecules in organic synthesis. While it has been successfully implemented in diastereoselective synthesis of natural products and other complex compounds, radical cascade cyclization faces a major challenge of controlling enantioselectivity. As the first application of metalloradical catalysis (MRC) for controlling enantioselectivity as well as diastereoselectivity in radical cascade cyclization, we herein report the development of a Co(II)-based catalytic system for asymmetric radical bicyclization of 1,6-enynes with diazo compounds. Through the fine-tuning of D2-symmetric chiral amidoporphyrins as the supporting ligands, the Co(II)-catalyzed radical cascade process, which proceeds in a single operation under mild conditions, enables asymmetric construction of multisubstituted cyclopropane-fused tetrahydrofurans bearing three contiguous stereogenic centers, including two all-carbon quaternary centers, in high yields with excellent stereoselectivities. Combined computational and experimental studies have shed light on the underlying stepwise radical mechanism for this new Co(II)-based cascade bicyclization that involves the relay of several Co-supported C-centered radical intermediates, including α-, β-, γ-, and ?-metalloalkyl radicals. The resulting enantioenriched cyclopropane-fused tetrahydrofurans that contain a trisubstituted vinyl group at the bridgehead, as showcased in several stereospecific transformations, may serve as useful intermediates for stereoselective organic synthesis. The successful demonstration of this new asymmetric radical process via Co(II)-MRC points out a potentially general approach for controlling enantioselectivity as well as diastereoselectivity in synthetically attractive radical cascade reactions.
Palladium-catalyzed arylation of methyl 2-(acetoxymethyl)acrylate: A convenient synthesis of rearranged Morita-Baylis-Hillman acetates
Kim, Ko Hoon,Lim, Jin Woo,Lee, Hyun Ju,Kim, Jae Nyoung
, p. 419 - 423 (2013/02/25)
Palladium-catalyzed arylation of methyl 2-(acetoxymethyl)acrylate with aryl iodides afforded the primary acetates of Morita-Baylis-Hillman adducts in good yields with high stereoselectivity under mild conditions (50°C).
Iridium-catalyzed asymmetric hydrogenation yielding chiral diarylmethines with weakly coordinating or noncoordinating substituents
Tolstoy, Paeivi,Engman, Mattias,Paptchikhine, Alexander,Bergquist, Jonas,Church, Tamara L.,Leung, Abby W.-M.,Andersson, Pher G.
supporting information; experimental part, p. 8855 - 8860 (2009/12/04)
Diarylmethine-containing stereocenters are present in pharmaceuticals and natural products, making the synthetic methods that form these chiral centers are important in industry. We have applied iridium complexes with novel N,P-chelating ligands to the asymmetric hydrogenation of trisubstituted olefins, forming diarylmethine chiral centers in high conversions and excellent enantioselectivities (up to 99% ee) for a broad range of substrates. Our results support the hypothesis that steric hindrance in one specific area of the catalyst is playing a key role in stereoselection, as the hydrogenation of substrates differing little at the prochiral carbon occurred with high enantioselectivity. As a result, excellent stereodiscrimination was obtained even when the prochiral carbon bore, for example, phenyl and p-tolyl groups.
