Asymmetric processes

Chiral Amino Siloxy Dienes in the Diels−Alder Reaction: Applications to the Asymmetric Synthesis of 4-Substituted and 4,5-Disubstituted Cyclohexenones and the Total Synthesis of (−)-α-Elemene

“…An appreciation of these factors not only allows the stereochemical outcome of the reactions to be rationalized but also provides a mechanistic framework for further development of the transformation being studied. An important step in understanding the enantioselection process is the development and testing of simple, reliable models that allow the prediction of the chiral induction . With a good model the reaction can be incorporated with confidence in the asymmetric synthesis of complex targets…”

Applications of oxazolidinones as chiral auxiliaries in the asymmetric alkylation reaction applied to total synthesis

“…Furthermore Evans' oxazolidinones are applicable in asymmetric anti-aldol reactions, Michael addition, the addition to C]O and C]N bonds and cycloaddition etc. 15,16 It is observed that the steric hindrance of substituents at 4 and 5 positions of oxazolidinones control the stereoselectivities of many alkylations of enolates.…”

“…Numerous highly diastereoselective reactions including asymmetric aldol reactions, alkylations, cycloadditions, Michael additions, aminations, azidations, brominations, hydroxylations, Diels-Alder reactions, and 1,4conjugate additions have been successfully accomplished, using diverse Evans chiral oxazolidinones as chiral auxiliaries. [15][16][17][18][19] They are derived from the corresponding a-amino acids. They are the most popular auxiliaries for the conduction of efficient asymmetric syntheses, being frequently used for stereoselective C-C and C-X (X ¼ O, N, Br, F, etc.)…”

Synthesis and application of 3‐substituted (S)‐BINOL as chiral ligands for the asymmetric ethylation of aldehydes

“…Enantioselective construction of carbon–carbon bonds is one of the most important and vigorously pursued areas in organic chemistry 1–7. Since the pioneering work of Oguni et al in 1984,8, 9 asymmetric ethylation of carbonyl compounds in the presence of catalytic amounts of chiral ligands has attracted great attention in recent years,10–19 not only because it is an effective and excellent method to form chiral carbon–carbon bonds but also because the products, optically active alcohols, are valuable building blocks for many naturally occurring compounds, pharmacologically and biologically interesting molecules 20–23.…”