scholarly journals Role of Additives to Overcome Limitations of Intermolecular Rhodium-Catalyzed Asymmetric Cyclopropanation

2021 ◽  
Author(s):  
Jack C. Sharland ◽  
Bo Wei ◽  
David J. Hardee ◽  
Timothy R Hodges ◽  
Wei Gong ◽  
...  
Keyword(s):  
Chiral Auxiliary ◽  
Asymmetric Induction ◽  
Asymmetric Cyclopropanation ◽  
Enantioselective Syntheses

This study describes general methods for the enantioselective syntheses of disubstituted cyclopropane carboxylates including substitution patterns or heterocycle functionality previously observed as significant limitations. The key step is the dirhodium tetracarboxylate-catalyzed asymmetric cyclopropanation of vinyl arenes with aryl- or heteroaryldiazoacetates. The reactions are highly diastereoselective and high asymmetric induction could be achieved using either (<i>R</i>)-pantolactone as a chiral auxiliary or chiral dirhodium tetracarboxylate catalysts.

scholarly journals Role of Additives to Overcome Limitations of Intermolecular Rhodium-Catalyzed Asymmetric Cyclopropanation

2021 ◽  
Author(s):  
Jack C. Sharland ◽  
Bo Wei ◽  
David J. Hardee ◽  
Timothy R Hodges ◽  
Wei Gong ◽  
...  
Keyword(s):  
Chiral Auxiliary ◽  
Asymmetric Induction ◽  
Asymmetric Cyclopropanation ◽  
Enantioselective Syntheses

This study describes general methods for the enantioselective syntheses of disubstituted cyclopropane carboxylates including substitution patterns or heterocycle functionality previously observed as significant limitations. The key step is the dirhodium tetracarboxylate-catalyzed asymmetric cyclopropanation of vinyl arenes with aryl- or heteroaryldiazoacetates. The reactions are highly diastereoselective and high asymmetric induction could be achieved using either (<i>R</i>)-pantolactone as a chiral auxiliary or chiral dirhodium tetracarboxylate catalysts.

Photochemistry of 9-methylbicyclo[3.3.1]nonyl aryl ketones — A novel 1,5-disproportionation of 1,4-hydroxy biradicals and asymmetric induction using the solid-state ionic chiral auxiliary method

2005 ◽  
Vol 83 (9) ◽  
pp. 1460-1472 ◽  
Author(s):  
Shuang Chen ◽  
Brian O Patrick ◽  
John R Scheffer
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Solid State Ionic ◽  
Chiral Auxiliary ◽  
Asymmetric Induction ◽  
X Ray Crystallography ◽  
Aryl Ketones ◽  
Hydroxy Biradicals ◽  
Phenyl Ketones ◽  
State Ionic

A novel 1,5-disproportionation reaction has been discovered for 1,4-hydroxy biradicals derived from the photolysis of 9-methylbicyclo[3.3.1]nonyl phenyl ketones (1), which undergo mainly Yang cyclization both in solution and the solid state. By applying the solid-state ionic chiral auxiliary method of asymmetric synthesis to the Yang cyclization, enantiomeric excesses as high as 95% were achieved at high reaction conversions. The origin of the reaction selectivity is discussed with the help of X-ray crystallography. In addition, the solid-state photoreaction of ketone 1b was found to occur in a single crystal-to-single crystal fashion.Key words: photochemistry, 1,4-hydroxy biradical, disproportionation, asymmetric induction, ionic chiral auxiliary, single crystal-to-single crystal reaction.

Synthesis and catalytic activity of 10-(aminomethyl)isoborneol-based catalysts: the role of the C(2)-group on the asymmetric induction

2003 ◽  
Vol 14 (14) ◽  
pp. 1959-1963 ◽  
Author(s):  
Antonio Garcı́a Martı́nez ◽  
Enrique Teso Vilar ◽  
Amelia Garcı́a Fraile ◽  
Santiago de la Moya Cerero ◽  
Beatriz Lora Maroto
Keyword(s):  
Catalytic Activity ◽  
Asymmetric Induction

scholarly journals N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

2019 ◽  
Vol 15 ◽  
pp. 1722-1757
Author(s):  
Iwona E Głowacka ◽  
Aleksandra Trocha ◽  
Andrzej E Wróblewski ◽  
Dorota G Piotrowska
Keyword(s):  
Amino Acids ◽  
Natural Products ◽  
Natural Compounds ◽  
Review Article ◽  
Chiral Auxiliary ◽  
Biologically Relevant ◽  
Alternative Approaches ◽  
Approved Drugs ◽  
Enantioselective Syntheses ◽  
New Procedures

Since Garner’s aldehyde has several drawbacks, first of all is prone to racemization, alternative three-carbon chirons would be of great value in enantioselective syntheses of natural compounds and/or drugs. This review article summarizes applications of N-(1-phenylethyl)aziridine-2-carboxylates, -carbaldehydes and -methanols in syntheses of approved drugs and potential medications as well as of natural products mostly alkaloids but also sphingoids and ceramides and their 1- and 3-deoxy analogues and several hydroxy amino acids and their precursors. Designed strategies provided new procedures to several drugs and alternative approaches to natural products and proved efficiency of a 2-substituted N-(1-phenylethyl)aziridine framework as chiron bearing a chiral auxiliary.

ChemInform Abstract: Highly Diastereoselective Diels-Alder Reaction Mediated by a Chiral Auxiliary Derived from Amino Indanol: The Role of Conformation on Diastereoselectivity.

ChemInform ◽  
2010 ◽  
Vol 27 (5) ◽  
pp. no-no
Author(s):  
I. W. DAVIES ◽  
C. H. SENANAYAKE ◽  
L. CASTONGUAY ◽  
R. D. LARSEN ◽  
T. R. VERHOEVEN ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Chiral Auxiliary ◽  
Diels Alder Reaction

Asymmetric Induction in Darzens Condensation by Means of (R)-5,5- Dimethyl-4-Phenyloxazolidin-2-One as an Effective Chiral Auxiliary

2007 ◽  
Vol 4 (4) ◽  
pp. 228-231 ◽  
Author(s):  
Abed Badrian ◽  
Manouchehr Mamaghani ◽  
Khalil Tabatabaeian ◽  
Hassan Valizadeh
Keyword(s):  
Chiral Auxiliary ◽  
Asymmetric Induction ◽  
Darzens Condensation
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