Asymmetric Ring Opening Research Articles

Chiral palladacycle catalysts generated on a single-handed helical polymer skeleton for asymmetric arylative ring opening of 1,4-epoxy-1,4-dihydronaphthalene.

Post-polymerization CH activation of poly(quinoxaline-2,3-diyl)-based helically chiral phosphine ligands (PQXphos) with palladium(II) acetate afforded chiral phosphapalladacycles quantitatively. In situ generated palladacycles exhibited enantioselectivities up to 94 % ee in the palladium-catalyzed asymmetric ring-opening arylation of 1,4-epoxy-1,4-dihydronaphthalenes with arylboronic acids.

ChemInform Abstract: Catalytic Asymmetric Nucleophilic Openings of 3‐Substituted Oxetanes

AbstractReview: [10 refs.

Asymmetric Alkynylative Ring Opening Reaction of Oxabenzonorbornadienes Promoted by Palladium/Silver Cocatalytic System

AbstractThe combination of palladium(II) acetate/(R)‐xylyl‐Phanephos and silver triflate (Pd:Ag=1:1) was found to be an efficient catalytic system for the asymmetric ring opening reactions of oxabenzonorbornadienes with terminal alkynes. The products were typically afforded in good yields (up to 95% yield) and with high enantioselectivities (up to 99% ee).magnified image

Asymmetric Ring Opening–Cross-Metathesis of Cyclobutene-diols

Asymmetric Ring Opening–Cross-Metathesis of Cyclobutene-diols

Conformationally Rigid Chiral Bicyclic Skeleton‐Tethered Bipyridine N,N′‐Dioxide as Organocatalyst: Asymmetric Ring Opening of meso‐Epoxides

AbstractThe conformationally rigid chiral bicyclic skeleton tethered bipyridine N,N′‐dioxide (−)‐9 has been designed, synthesized and examined as an organocatalyst in the enantioselective ring opening of meso‐epoxides using tetrachlorosilane (SiCl4). The catalyst (−)‐9 is found to exhibit good enantioselectivity for substituted cis‐stilbene epoxides; whereas, the saturated cyclic meso‐epoxides display a moderate enantioselectivity. At −30 °C in chloroform, the catalyst (−)‐9 with 0.5 mol % loading generated the chlorohydrins in up to 97 % yield with up to 93 % ee. The possible creation of transient axial chiral environment around hypervalent silicon species due to the presence of conformationally rigid chiral bicyclic skeleton tethered bipyridine N,N′‐dioxide may be responsible for such enantioselectivity observed in the desymmetrization of meso‐epoxides.magnified image

Inside Cover: Design of Peptidyl Thiourea Derivatives as Organocatalysts for the Asymmetric Ring Opening ofmeso-Stilbene Oxides (Asian J. Org. Chem. 6/2014)

Organocatalysis Organocatalytic asymmetric ring opening of epoxides with aliphatic amines has always been a challenge. In their Communication on page 700 ff., Swapandeep Singh Chimni report the design and synthesis of chiral peptidyl thiourea organocatalysts for the asymmetric ring opening of epoxides with N-phenylpiperazines. A tripeptide scaffold with a β-turn nucleating element provides favorable stereochemistry by positioning the nucleophile close to the epoxide. Chiral β-amino alcohols were obtained with up to 95% ee after crystallization. The configuration at the N-terminal residue of the catalyst affects the stereochemical outcome of the reaction.

Nickel-catalyzed asymmetric ring opening of oxabenzonorbornadienes with arylboronic acids.

A new, versatile, and highly efficient nickel-catalyzed asymmetric ring-opening (ARO) reaction of oxabenzonorbornadienes with a wide variety of arylboronic acids has been developed, yielding cis-2-aryl-1,2-dihydronaphthalen-1-ols in high yields (up to 99%) with good to excellent enantioselectivities (up to 99% ee) under very mild conditions. The effects of various nickel precursors, chiral bidentate ligands, catalyst loadings, bases, solvents, and temperatures on the yield and enantioselectivity of the reaction were also investigated. A plausible mechanism was proposed to account for the formation of the corresponding cis-ring-opened products based on the X-ray structure of product 4b.

Unravelling a new class of chiral organocatalyst for asymmetric ring-opening reaction of meso epoxides with anilines.

Chiral sulfinamide based organocatalyst 11 was synthesized from readily available starting materials and used for the asymmetric ring-opening (ARO) reaction of meso epoxides with anilines. A high yield (up to 95%) of chiral β-amino alcohols with excellent enantioselectivity (ee up to 99%) was achieved in 24-30 h at rt under optimized reaction conditions. A probable mechanism for the catalytic ARO reaction is envisaged by (1)H and (13)C NMR experiments.

Asymmetric ring opening of epoxides with cyanides catalysed by chiral binuclear titanium complexes

A series of Schiff bases obtained from salicylaldehydes and 3,3′-diformyl-BINOL were synthesized. The complexes of these Schiff bases with Ti(IV) were active for the asymmetric ring opening of epoxides with TMSCN. A mixture of unpurified ligands was found to be as effective as the best one. The influence of temperature, solvent polarity and structural modification of the pre-catalysts on the enantioselectivity of the process has also been investigated.

Design of Peptidyl Thiourea Derivatives as Organocatalysts for the Asymmetric Ring Opening of meso‐Stilbene Oxides

AbstractChiral peptidyl thiourea organocatalysts were designed and synthesized for asymmetric ring‐opening of cis‐stilbene oxides with N‐phenylpiperazines. Chiral β‐amino alcohols were obtained with up to 95 % ee after crystallization. The configuration at the N‐terminal residue stereogenic center of peptidyl thiourea organocatalyst was found to affect the stereochemical outcome of the reaction.

Sidearm as a Control in the Asymmetric Ring Opening Reaction of Donor‐Acceptor Cyclopropane

AbstractA new type of trisoxazoline and bisthiazoline based ligands have been developed,which are absent of chiral motif on the parent skeleton and containa chiral backbone on sidearm. The ligands promote the amine nucleophilic ring opening reaction of 1,1‐cyclopropane diesters smoothly, furnishing the γ‐amino acid derivatives in high yield with moderate to good enantioselectivity.

ChemInform Abstract: Asymmetric Ring Opening of meso‐Epoxides with Aromatic Amines Using (R)‐(+)‐BINOL‐Sc(OTf)3‐NMM Complex as an Efficient Catalyst.

AbstractInexpensive and simple starting materials are used for the in situ generation of the highly efficient title complex.

ChemInform Abstract: Catalytic Asymmetric Ring‐Opening of δ‐Symmetric Cyclic Carbonates with Chiral Broensted Acid Catalysts.

ChemInformVolume 45, Issue 10 Preparative Organic Chemistry ChemInform Abstract: Catalytic Asymmetric Ring-Opening of δ-Symmetric Cyclic Carbonates with Chiral Broensted Acid Catalysts. Shigeki Sano, Shigeki Sano Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this authorTakeshi Tsumura, Takeshi Tsumura Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this authorMasashi Horibe, Masashi Horibe Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this authorMichiyasu Nakao, Michiyasu Nakao Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this author Shigeki Sano, Shigeki Sano Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this authorTakeshi Tsumura, Takeshi Tsumura Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this authorMasashi Horibe, Masashi Horibe Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this authorMichiyasu Nakao, Michiyasu Nakao Grad. Sch. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770-8505, JapanSearch for more papers by this author First published: 21 February 2014 https://doi.org/10.1002/chin.201410031Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume45, Issue10March 11, 2014 RelatedInformation

ChemInform Abstract: Asymmetric Ring‐Opening of Oxabenzonorbornadiene with Amines Promoted by a Chiral Iridium‐Monophosphine Catalyst

Abstract28 examples

Iron-Catalyzed Asymmetric Ring Opening of meso-Epoxides

Iron-Catalyzed Asymmetric Ring Opening of meso-Epoxides

Catalytic asymmetric nucleophilic openings of 3-substituted oxetanes.

Asymmetric ring-opening of 3-substituted oxetanes provides rapid access to highly functionalized chiral building blocks. However, progress in this field is limited. Recently we developed a new catalytic system based on chiral Brønsted acids for this type of reaction and demonstrated the synthesis of a range of useful molecules under mild and operationally simple conditions. In this perspective, we describe the challenges, progress, and potential future efforts on this topic.

Chiral magnesium(II)-catalyzed asymmetric ring-opening of meso-aziridines with primary alcohols.

The asymmetric ring-opening of meso-aziridines with primary alcohols is realized using an N,N'-dioxide-Mg(OTf)2 complex as the catalyst. The desired vicinal trans-β-amino ethers are afforded in good yields and enantioselectivities. Aniline and water could also be used as the nucleophiles for the ring-opening in an identical catalyst system.

Iridium-Catalyzed Asymmetric Ring-Opening of Oxabicyclic Alkenes with Carboxylic Acids

A novel iridium-catalyzed asymmetric ring-opening of oxabicyclic alkenes with a variety of carboxylic acids was reported, which afforded the corresponding trans-carboxylic acids 1-hydroxy-1,2-dihydro-naphthalen-2-yl ester products in good yields with moderate enantioselectivities under mild conditions. The trans products are formed via the enantioselective cleavage of a bridgehead carbon–oxygen bond in 1 followed by SN2′ nucleophilic attack by carboxylic acids. The effects of various bisphosphine ligands, Ag(I) salts, ammonium halides, bases, and solvents on the yields and enantioselectivities of the reaction were also investigated. The theoretical analysis of stability and hydrogen bond for 1-hydroxy-1,2-dihydronaphthalen-2-yl 4-chlorobenzoate 2a were performed using the density functional theory B3LYP methods. The trans-configuration of the product 2a was confirmed by X-ray diffraction analysis. A possible mechanism for the present catalytic reaction was proposed. A novel iridium-catalyzed asymmetric ring-opening of oxabicyclic alkenes with a variety of carboxylic acids was reported, which afforded the corresponding trans-carboxylic acids 1-hydroxy-1,2-dihydro-naphthalen-2-yl ester products in good yields with moderate enantioselectivities under mild conditions. The trans products are formed via the enantioselective cleavage of a bridgehead carbon–oxygen bond in 1 followed by SN2′ nucleophilic attack by carboxylic acids. The effects of various bisphosphine ligands, Ag(I) salts, ammonium halides, bases, and solvents on the yields and enantioselectivities of the reaction were also investigated. The theoretical analysis of stability and hydrogen bond for 1-hydroxy-1,2-dihydronaphthalen-2-yl 4-chlorobenzoate 2a were performed using the density functional theory B3LYP methods. The trans-configuration of the product 2a was confirmed by X-ray diffraction analysis. A possible mechanism for the present catalytic reaction was proposed.

Enantioselective Palladium‐Catalyzed Ring‐Opening Reaction of Azabenzonorbornadienes with Methyl 2‐Iodobenzoate: An Efficient Access to cis‐Dihydrobenzo[c]phenanthridinones

AbstractThe palladium‐catalyzed asymmetric ring‐opening (ARO) reaction of azabenzonorbornadienes with iodobenzoate derivatives was realized by using chiral spirophosphine ligands with zinc powder as a reducing reagent. Various enantiomerically enriched cis‐dihydrobenzo[c]phenanthridinones, the core structure of numerous chiral natural products, were prepared by the ARO reaction and tandem amidation from easily obtained starting materials with favorable enantioselectivity (up to 86% ee) under mild reaction conditions. The present palladium‐catalyzed ARO reaction avoids the direct use of organometallic reagents, enables tandem cyclization, and thus improves synthetic efficiency. The formal total synthesis of a chiral natural product, (+)‐chelidonine, was accomplished with the ARO reaction as a key step, which demonstrates the potential synthetic applications of the present methodology.magnified image

Palladium/Copper Complexes Co‐Catalyzed Highly Enantioselective Ring Opening Reaction of Azabenzonorbornadienes with Terminal Alkynes

AbstractA chiral palladium/copper (Pd/Cu) co‐catalytic system which could enable asymmetric ring opening reaction of azabenzonorbornadienes with terminal alkynes is reported. This system comprises palladium(II) acetate [Pd(OAc)2]/(R)‐xyl‐Binap and copper(I) triflate (CuOTf). A good substrate scope was found, with excellent enantioselective outcomes (up to >99.9 % ee). A reaction mechanism involving two metal complexes is also proposed.magnified image