Enantioselective Cyclopropanation with TADDOL‐Derived Phosphate Ligands

Voituriez, Arnaud; Charette, André B.

doi:10.1002/adsc.200600351

Cited by 47 publications

(22 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Silver(I) complexes 1‐Ag and 2‐Ag were prepared from the reactions of Ag 2 CO 3 with β‐CgPOOH ( 1‐H )8, 9 and TADDOL‐POOH ( 2‐H ),10 respectively. These complexes, which were isolated as white solids and were soluble in most organic solvents, were fully characterised.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Silver‐Catalysed Enantioselective Addition of OH and NH Bonds to Allenes: A New Model for Stereoselectivity Based on Noncovalent Interactions

Arbour

Rzepa

Contreras‐García

et al. 2012

Chemistry A European J

View full text Add to dashboard Cite

The ability of silver complexes to catalyse the enantioselective addition of O-H and N-H bonds to allenes is demonstrated for the first time by using optically active anionic ligands that were derived from oxophosphorus(V) acids as the sources of chirality. The intramolecular addition of acids, alcohols, and amines to allenes can be achieved with up to 73% ee. The exploitation of a C-H anomeric effect allowed the absolute configuration of a sample of 2-substituted tetrahydrofuran of low ee to be unambiguously assigned by comparison of the chiroptical ORD and VCD measurements with calculated spectra. In the second part of the work, the origin of the stereoselectivity was probed by DFT free-energy calculations of the transition states. A new model of enantiomeric differentiation was developed that was based on noncovalent interactions. This model allowed us to identify the source of stereoselectivity as weak attractive interactions; such dispersive forces are often overlooked in asymmetric catalysis. A new computational approach was developed that represents these interactions as colour-coded isosurfaces that are characterised by the reduced density-gradient profile.

show abstract

Section: Resultsmentioning

confidence: 99%

“…Synthesis of 2‐Ag (method 2) : Ag 2 CO 3 (0.5 equiv) was added in a single portion to a solution of 2‐H 10 (1 equiv) in CH 2 Cl 2 (5 mL) followed by H 2 O (5 mL). The resulting mixture was protected from light and stirred vigorously for 2 h. After this time, the mixture was diluted with CH 2 Cl 2 (10 mL) and H 2 O (10 mL).…”

Section: Methodsmentioning

confidence: 99%

Silver‐Catalysed Enantioselective Addition of OH and NH Bonds to Allenes: A New Model for Stereoselectivity Based on Noncovalent Interactions

Arbour

Rzepa

Contreras‐García

et al. 2012

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Although this report clearly demonstrated the feasibility of this strategy, and although the corresponding catalysts could be systematically fine-tuned and synthesized in a straightforward fashion, these catalysts have so far been used only to a limited extent. Whereas Charette’s group successfully employed them as ligands in Zn-mediated asymmetric cyclopropanation reactions,21 List et al tested them as chiral Brønsted acids in recent investigations into asymmetric spiroacetalization and transacetalization reactions 22. In these special cases, however, the TADDOL-derived phosphoric acids only gave racemic products, whereas other skeletons were found to be much more selective 22…”

Section: Chiral Brønsted Acids and H-bonding Donorsmentioning

confidence: 99%

Towards Tartaric‐Acid‐Derived Asymmetric Organocatalysts

2013

View full text Add to dashboard Cite

Tartaric acid is one of the most prominent naturally occurring chiral compounds. Whereas its application in the production of chiral ligands for metal-catalysed reactions has been exhaustively investigated, its potential to provide new organocatalysts has been less extensively explored. Nevertheless, some impressive results, such as the use of TADDOLs as chiral H-bonding catalysts or of tartrate-derived asymmetric quaternary ammonium salt catalysts, have been reported over the last decade. The goal of this article is to provide a representative overview of the potential and the limitations of tartaric acid or TADDOLs in the creation of new organocatalysts and to highlight some of the most spectacular applications of these catalysts, as well as to summarize case studies in which other classes of chiral backbones were better suited.

show abstract

“…The Simmons‐Smith cyclopropanation has been frequently employed in the stereoselective cyclopropanation of olefins and allylic alcohols with chiral auxiliaries or with stoichiometric additives, and excellent stereoselectivities have been reported . However, the development of catalytic enantioselective Simmons‐Smith cyclopropanations remains challenging . In particular, the asymmetric cyclopropanation of allylic alcohols suffers from suboptimal enantioselectivities and high catalyst loadings with moderate substrate scope .…”

Section: Introductionmentioning

confidence: 99%

Tandem catalytic enantio‐ and diastereoselective synthesis of cyclopropyl alcohols using aryl aldehydes

Kim

Walsh

2012

J of Physical Organic Chem

View full text Add to dashboard Cite

The prevalence of cyclopropanes in biologically active compounds has fueled many investigations into their preparation. Despite significant advances, more efficient methods for their catalytic enantioselective synthesis remain in demand. Previously, we reported a novel tandem approach to diastereo‐ and enantioenriched cyclopropyl alcohols. Our method involved an initial asymmetric C–C bond formation by addition of organozinc reagents to aldehydes catalyzed by a (−)‐MIB‐based catalyst. The resulting allylic zinc alkoxides were then subject to directed cyclopropanations. Although this approach provided cyclopropyl alcohols with very high enantio‐ and diastereoselectivity, it was successful with only aliphatic aldehydes. Aryl aldehyde substrates, on the other hand, exhibited low conversion and variable diastereomeric ratios. The present study is aimed at raising the stereoselectivity and yield of the aforementioned tandem reaction with aryl aldehyde substrates to make the method synthetically useful. Herein, we report the successful optimization of aryl aldehyde substrates in our one‐pot tandem approach leading to cyclopropyl alcohols with high yields and enantio‐ and diastereoselectivities. Copyright © 2012 John Wiley & Sons, Ltd.

show abstract

Enantioselective Cyclopropanation with TADDOL‐Derived Phosphate Ligands

Cited by 47 publications

References 57 publications

Silver‐Catalysed Enantioselective Addition of OH and NH Bonds to Allenes: A New Model for Stereoselectivity Based on Noncovalent Interactions

Silver‐Catalysed Enantioselective Addition of OH and NH Bonds to Allenes: A New Model for Stereoselectivity Based on Noncovalent Interactions

Towards Tartaric‐Acid‐Derived Asymmetric Organocatalysts

Tandem catalytic enantio‐ and diastereoselective synthesis of cyclopropyl alcohols using aryl aldehydes

Contact Info

Product

Resources

About