140834-50-0Relevant articles and documents
The atropo-enantioselective ring opening of achiral lactone-bridged biaryls using chirally modified aluminum hydrides
Bringmann,Hartung
, p. 433 - 435 (1992)
The atropo-enantioselective preparation of the chiral biaryl 2-hydroxymethyl-1-(2-hydroxy-4,6-dimethoxyphenyl)naphthalene (7) from 1,3-dimethoxy-6H-benzo[b]naphtho[1,2-d]pyran-6-one (3) is described, whereby two formal problems of stereoselective biaryl synthesis are independently solved: The carbon-carbon bond formation by the intramolecular aryl coupling of the ester-type prefixed aromatic halves, and the asymmetric induction at the pre-formed biaryl axis by the subsequent stereoselective ring-opening reaction, using chiral hydrogen nucleophiles.
Synthesis and applications of oxaspiro PNN ligand
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Paragraph 0026; 0056-0058, (2019/10/01)
The invention belongs to the field of chiral synthesis, and specifically provides synthesis of a class of novel oxaspiro PNN ligands. According to the synthesis, oxaspiro diphenol is used as a starting raw material, and trifluoromethyl sulfonylation, palladium-catalyzed diarylphosphine oxide coupling, trichlorosilane reduction, palladium-catalyzed carbon insertion esterification, hydrolysis, amination, reductive amination and other steps are performed to synthesize the novel oxaspiro PNN ligand. According to the present invention, the oxaspiro compound has central chirality, such that the novel oxaspiro PNN ligands comprise the levo-oxaspiro PNN ligand and the dextro-oxaspiro PNN ligand, and the racemic oxaspiro PNN ligand can be synthesized by using the racemic oxaspiro diphenol as the raw material; and the PNN ligand can be used as the chiral ligand for the asymmetric hydrogenation of ketone and lactone, wherein the complex of the ligand and iridium can respectively obtain the enantioselectivity of more than 98% and more than 99% in the asymmetric hydrogenation of simple ketones and lactones.
Atropo-enantioselective total synthesis of knipholone and related antiplasmodial phenylanthraquinones
Bringmann, Gerhard,Menche, Dirk,Kraus, Juergen,Muehlbacher, Joerg,Peters, Karl,Peters, Eva-Maria,Brun, Reto,Bezabih, Merhatibeb,Abegaz, Berhanu M.
, p. 5595 - 5610 (2007/10/03)
The "lactone concept" has been efficiently employed for the first atropo-enantioselective synthesis of knipholone and related natural phenylanthraquinones. Besides the regio- and stereoselective construction of the biaryl axis, another important step was the "synthetically late" introduction of the C-acetyl group, either by a Friedel-Crafts type acetylation or by an ortho-selective Fries rearrangement first tested on simplified model systems and subsequently applied to the highly atroposelective preparation of the natural products and of simplified analogs thereof for biotesting. The synthetic availability of these natural biaryls, their precursors, and their unnatural analogs permitted a broader investigation of the antiplasmodial activities of these interesting biaryls.
The atropo-enantioselective reduction of configurationally unstable biaryl hydroxy aldehydes - A novel approach to axially chiral biaryls
Bringmann, Gerhard,Breuning, Matthias
, p. 634 - 636 (2007/10/03)
The oxazaborolidine-assisted atropo-enantioselective catecholborane reduction of configurationally unstable biaryl hydroxy aldehydes to axially chiral biaryl alcohols by (dynamic) kinetic resolution is achieved in enantiomeric ratios (er) of up to 92:8. Using the same chiral auxiliary, the M- or, optionally, the P-configurated atropisomer can be obtained in good er's - just by variation of the relative quantity of the achiral reductant. This hints at the existence of two competing reaction pathways with opposite asymmetric inductions. The enantiomeric ratios observed strongly depend on the relative steric demand of the substituents ortho to the biaryl axis.
