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Stereoisomerism

About: Stereoisomerism is a research topic. Over the lifetime, 960 publications have been published within this topic receiving 30821 citations.


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Journal ArticleDOI
TL;DR: Equilibrium binding studies and viscosity experiments are described that characterize the interaction of delta- and lambda-[Ru(o-phen)3]2+ with calf thymus DNA to show quantitatively that both the delta and lambda isomers are essentially electrostatically bound to DNA.
Abstract: Equilibrium binding studies and viscosity experiments are described that characterize the interaction of delta- and lambda-[Ru(o-phen)3]2+ with calf thymus DNA. The mode of binding of these compounds to DNA is a matter of controversy. Both isomers of [Ru(o-phen)3]2+ were found to bind but weakly to DNA, with binding constants of 4.9 (+/- 0.3) x 10(4) M-1 and 2.8 (+/- 0.2) x 10(4) M-1 determined for the delta and lambda isomers, respectively, at 20 degrees C in a solution containing 5 mM Tris-HCl (pH 7.1) and 10 mM NaCl. We determined that the quantity delta log K/delta log [Na+] equals 1.37 and 1.24 for the delta and lambda isomers, respectively. Application of polyelectrolyte theory allows us to use these values to show quantitatively that both the delta and lambda isomers are essentially electrostatically bound to DNA. Viscosity experiments show that binding the lambda isomer does not alter the relative viscosity of DNA to any appreciable extent, while binding of the delta isomer decreases the relative viscosity of DNA. From these viscosity results, we conclude that neither isomer of [Ru(o-phen)3]2+ binds to DNA by classical intercalation.

1,263 citations

Journal ArticleDOI
30 May 1986-Science
TL;DR: These studies have improved the understanding and application of the chiral interactions of beta-cyclodextrin, and they have demonstrated a means to measure optical purity and to isolate or produce pure enantiomers of drugs.
Abstract: For many drugs, only racemic mixtures are available for clinical use. Because different stereoisomers of drugs often cause different physiological responses, the use of pure isomers could elicit more exact therapeutic effects. Differential complexation of a variety of drug stereoisomers by immobilized beta-cyclodextrin was investigated. Chiral recognition and racemic resolution were observed with a number of compounds from such clinically useful classes as beta-blockers, calcium-channel blockers, sedative hypnotics, antihistamines, anticonvulsants, diuretics, and synthetic opiates. Separation of the diastereomers of the cardioactive and antimalarial cinchona alkaloids and of two antiestrogens was demonstrated as well. Three dimensional projections of beta-cyclodextrin complexes of propanolol, which is resolved by this technique, and warfarin, which is not, are compared. These studies have improved the understanding and application of the chiral interactions of beta-cyclodextrin, and they have demonstrated a means to measure optical purity and to isolate or produce pure enantiomers of drugs. In addition, this highly specific technique could also be used in the pharmacological evaluation of enantiomeric drugs.

569 citations

Journal ArticleDOI
TL;DR: A proof of concept is demonstrated by the design of a Pd/amino acid complex capable of catalyzing asymmetric activation of prochiral C H and C(sp) H bonds to form chiral products with new C C bonds in excellent enantioselectivity.
Abstract: Enantioselective C H activation has been a longstanding challenge in catalysis and organic chemistry. The insertion of metal-bound carbenes or nitrenes into C H bonds has been employed to develop highly enantioselective carbon–carbon and carbon–nitrogen bond-forming reactions. The enantioselective lithiation of C(sp) H bonds adjacent to the nitrogen atom in N-tert-butyloxycarbonylpyrrolidine using secBuLi/( )sparteine has provided a broadly useful method for the differentiation of prochiral C(sp) H bonds. Investigations into the biomimetic oxidation of C H bonds using chiral metal–porphyrin complexes and other synthetic catalysts continue to provide inspiration for the development of methods for the asymmetric oxidation of C H bonds. Remarkable progress in understanding the fundamental mechanisms of C H activation by means of metal insertion has spurred the development of metal-catalyzed carbon– carbon and carbon–heteroatom bond-forming reactions in organic molecules containing functional groups. Such reactions will impact synthetic and medicinal chemistry in the context of retrosynthetic analysis by providing unprecedented and more efficient strategic disconnections. A major hurdle remaining in Pd-catalyzed C H activation reactions, however, is the need for an external ligand that coordinates to the Pd species and controls the chemo-, regio-, and stereoselectivity of its insertion into C H bonds. With this in mind, we embarked on the development of a Pd-catalyzed enantioselective C H activation/C C coupling reaction, a process previously unknown owing to the difficulty in differentiating prochiral C H bonds through metal insertions. Herein we demonstrate a proof of concept by the design of a Pd/amino acid complex capable of catalyzing asymmetric activation of prochiral C(sp) H and C(sp) H bonds to form chiral products with new C C bonds in excellent enantioselectivity [Eq. (1)].

520 citations

Journal ArticleDOI
TL;DR: Under special conditions, N-phthaloyl-alpha-amino acid amides of 8-aminosquinoline can be either acetoxylated or arylated selectively at the beta-carbon.

455 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20233
20228
20217
202012
201911
201815