Chiral Pincer Carbodicarbene Ligands for Enantioselective Rhodium-Catalyzed Hydroarylation of Terminal and Internal 1,3-Dienes with Indoles
作者:Justin S. Marcum、Courtney C. Roberts、Rajith S. Manan、Tia N. Cervarich、Simon J. Meek
DOI:10.1021/jacs.7b08575
日期:2017.11.8
Catalytic enantioselective addition of N-heteroarenes to terminal and internal 1,3-dienes is reported. Reactions are promoted by 5 mol % of Rh catalyst supported by a new chiral pincer carbodicarbene ligand that delivers allylic substituted arenes in up to 95% yield and up to 98:2 er. Mechanistic and X-ray evidence is presented that supports that the reaction proceeds via a Rh(III)-η3-allyl.
Chiral Aminophosphines as Catalysts for Enantioselective Double-Michael Indoline Syntheses
作者:San N. Khong、Ohyun Kwon
DOI:10.3390/molecules17055626
日期:——
The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient acetylenes is an efficient process for the synthesis of many nitrogen-containing heterocycles. Because the resulting heterocycles contain at least one stereogenic center, this double-Michael reaction would be even more useful if an asymmetric variant of the reaction were to be developed. Aminophosphines can also facilitate the double-Michael reaction and chiral amines are more readily available in Nature and synthetically; therefore, in this study we prepared several new chiral aminophosphines. When employed in the asymmetric double-Michael reaction between ortho-tosylamidophenyl malonate and 3-butyn-2-one, the chiral aminophosphines produced indolines in excellent yields with moderate asymmetric induction.
Asymmetric induction reactions. IV. Palladium-catalyzed asymmetric allylations of chiral enamines bearing phosphine groups.
作者:Kunio HIROI、Jun ABE
DOI:10.1248/cpb.39.616
日期:——
The palladium-catalyzed asymmetric allylations of chiral enamines, derived from (S)-2-(diphenylphosphinomethyl)pyrrolidine, produced optically active α-allyl carbonyl compounds in high optical yields. The phosphino group in the chiral enamines presumably serves as a chiral ligand in these palladium-catalyzed reactions. In the transition states of π-allylpalladium complexes coordinated with the intramolecular phosphine group, the anionic counterparts or allylating reagents are considered to play an important role in controlling of the grade of the enantioselectivity.
Proline-Based P,O Ligand/Iridium Complexes as Highly Selective Catalysts: Asymmetric Hydrogenation of Trisubstituted Alkenes
作者:Denise Rageot、David H. Woodmansee、Benoît Pugin、Andreas Pfaltz
DOI:10.1002/anie.201104105
日期:2011.10.4
O joins the mix: P,O ligands (L1) form efficient iridiumcatalysts for the asymmetric hydrogenation of olefins. The proline‐derived ligands lead to high enantioselectivities with several classes of alkenes, most notably with α,β‐unsaturated carboxylic esters and ketones, where they match or even surpass the ee values reported for the best N,P and C,N ligands.