Corey-Chaykovsky Reaction Research Articles

Diastereoselective One-Pot Synthesis of Oxazolines Using Sulfur Ylides and Acyl Imines.

This work describes an extended version of the Corey-Chaykovsky reaction to access oxazolines using sulfur ylides and stable precursors of acyl imines. The reaction proceeds through a mixture of aziridines and oxazolines, which provides the trans-oxazolines following in situ Heine-type aziridine ring expansion upon treatment with BF3·OEt2. Following the same one-pot procedure, amidine imides react with the sulfur ylides to provide imidazolines.

Fluoromethylene Transfer from Diarylfluoromethylsulfonium Salts: Synthesis of Fluorinated Epoxides.

Diarylfluoromethyl sulfonium salts are efficient fluoromethylene transfer reagents equivalent to fluorocarbene, which is difficult to access. This was demonstrated by the development of a monofluorinated Johnson-Corey-Chaykovsky reaction with ketones and aldehydes, delivering uncommon 2-unsubstituted fluoroepoxides. This is the first evidence for the feasibility of sulfur fluoromethylylide and its action as a reaction intermediate.

Cinchona Alkaloids-Derivatives and Applications.

Major Cinchona alkaloids quinine, quinidine, cinchonine, and cinchonidine are available chiral natural compounds (chiral pool). Unlike many other natural products, these alkaloids are available in multiple diastereomeric forms which are separated on an industrial scale. The introduction discusses in short conformational equilibria, traditional separation scheme, biosynthesis, and de novo chemical syntheses. The second section concerns useful chemical applications of the alkaloids as chiral recognition agents and effective chiral catalysts. Besides the Sharpless ethers and quaternary ammonium salts (chiral PTC), the most successful bifunctional organocatalysts are based on 9-amino derivatives: thioureas and squaramides. The third section reports the main transformations of Cinchona alkaloids. This covers reactions of the 9-hydroxyl group with the retention or inversion of configuration. Specific Cinchona rearrangements enlarging [2.2.2]bicycle of quinuclidine to [3.2.2] products are connected to the 9-OH substitution. The syntheses of numerous esterification and etherification products are described, including many examples of bi-Cinchona alkaloid ethers. Further derivatives comprise 9-N-substituted compounds. The amino group is introduced via an azido function with the inversion of configuration at the stereogenic center C9. The 9-epi-amino-alkaloids provide imines, amides, imides, thioureas, and squaramides. The syntheses of 9-carbon-, 9-sulfur-, and 9-selenium-substituted derivatives are discussed. Oxidation of the hydroxyl group of any alkaloid gives ketones, which can be selectively reduced, reacted with Grignard reagents, or subjected to the Corey-Chaykovsky reaction. The alkaloids were also partially degraded by splitting C4'-C9 or N1-C8 bonds. In order to immobilize Cinchona alkaloids the transformations of the 3-vinyl group were often exploited. Finally, miscellaneous functionalizations of quinuclidine, quinoline, and examples of various metal complexes of the alkaloids are considered.

Understanding Regioselectivities of Corey–Chaykovsky Reactions of Dimethylsulfoxonium Methylide (DMSOM) and Dimethylsulfonium Methylide (DMSM) toward Enones: A DFT Study

The Corey–Chaykovsky reaction, using either in situ generated dimethylsulfoxonium methylide (DMSOM) or dimethylsulfonium methylide (DMSM) to react with ketones or aldehydes, is widely used in the synthesis of epoxides. However, when DMSOM and DMSM react with enones (such as chalcone), the former reactions give cyclopropanation products whereas the latter reactions still generate epoxides. DFT calculations have been carried out to understand these different regioselectivities. We found that the cyclopropanation pathways for both DMSOM and DMSM toward chalcone (a model for enones) start with rate‐determining and irreversible 1,4‐addition reactions, followed by easier intramolecular substitution reactions to give cyclopropanes. The overall activation free energies for cyclopropanation are 17.5 and 15.5 kcal/mol for DMSOM and DMSM, respectively. The epoxidation pathways for both DMSOM and DMSM have reversible 1,2‐addition reactions, followed by rate‐determining intramolecular substitution reactions to give epoxides. The computed barriers for the epoxidation are 23.0 and 13.3 kcal/mol for DMSOM and DMSM, respectively. Therefore, the cyclopropanation pathway is favored for DMSOM while epoxidation is preferred for DMSM. We attribute these different reaction scenarios to thermodynamic reasons that DMSOM is more stable than DMSM. The reaction pathways for reactions of other derivatives of DMSM toward enones have also been discussed.

Synthesis of azabicyclo[n.1.0]alkane-derived bifunctional building blocks via the Corey–Chaykovsky cyclopropanation

An efficient approach towards the synthesis of monoprotected azabicyclo[5.1.0]octane-derived conformationally restricted γ-amino acids and diamines is reported. Optimization of the conditions for the key Corey–Chaykovsky reaction allowed the construction of two isomeric methanoazepane frameworks on a multigram scale in 55–65% yield. Additionally, the developed approach was used in the three-step synthesis of 3,4-methano-β-proline and its diamine derivatives.

Domino Corey-Chaykovsky Reaction for One-Pot Access to Spirocyclopropyl Oxindoles.

The development of the sequential Corey-Chaykovsky reactions of isatins, spiroepoxy-, or spiroaziridine oxindoles with sulfur ylide has led to the discovery of a unique reaction mode that allows easy and direct one-pot access to a range of spirocyclopropyl oxindoles.

3,20-Dihydroxy-13α-19-norpregna-1,3,5(10)-trienes. Synthesis, structures, and cytotoxic, estrogenic, and antiestrogenic effects

New 3,20-dihydroxy-13α-19-norpregna-1,3,5(10)-trienes were synthesized. The effects of these compounds on breast cancer cells and ERα activation were investigated. The scaffold of compounds containing the six-membered ring D′ annulated at 16α,17α-positions was constructed via the Lewis acid catalyzed Diels-Alder reaction of butadiene with 3-methoxy-13α-19-norpregna-1,3,5(10),16-tetraen-20-one 5 under a pressure of 600 MPa. The hydrogenation of primary cyclohexene adduct 6 followed by the one-pot reduction–demethylation (DIBAH) gave target epimeric 3,20-dihydroxy steroids 8a and 8b. The Corey-Chaykovsky reaction of the same conjugated ketone 5 gave a 16α,17α-methylene-substituted compound. The reaction of the latter with DIBAH yielded 3,20(R,S)-dihydroxy-16α,17α-methyleno-13α-19-norpregna-1,3,5(10)-triene 10. The hydrogenation of the 16,17-double bond of compound 5 produced a mixture of 17α- and 17β-epimeric ketones, reduction–demethylation of which gave 3,20(S)-dihydroxy-13α,17α-19-norpregna-1,3,5(10)-triene 12a and 3,20(R)-dihydroxy-13α,17β-19-norpregna-1,3,5(10)-triene 12b. All compounds were fully characterized by 1D and 2D NMR, HRMS, and X-ray diffraction. All target compounds showed pronounced cytotoxic effect against MCF-7 breast cancer cells and NCI/ADR-RES doxorubicin-resistant cells at micromolar concentrations. The ERα-mediated luciferase reporter gene assay demonstrated that all compounds, except for compound 10, are ERα inhibitors, while cyclopropane compound 10 proved to be an ERα activator. Docking experiments showed that all compounds are well accommodated to LBD ERα but have some differences in the binding mode.

Synthesis of CF3-containing spiro-epoxyoxindoles via the Corey–Chaykovsky reaction of N-alkyl isatins with Ph2S+CH2CF3OTf−

CF3-containing spiro-epoxyoxindoles were successfully prepared via the Corey-Chaykovsky reaction of N-alkyl isatins with the ylide generated from Ph2S+CH2CF3OTf- with almost exclusive diastereoselectivity. Further derivatizations of these spiro-epoxyoxindoles were explored via a photochemical reaction or Lewis acid-promoted allylation.

New estrogen receptor antagonists. 3,20-Dihydroxy-19-norpregna-1,3,5(10)-trienes: Synthesis, molecular modeling, and biological evaluation

New estrogen receptor α (ERα) antagonists – 3,20-dihydroxy-19-norpregna-1,3,5(10)-trienes containing an additional carbocyclic ring D′ at the 16α,17α positions – were synthesized. The effects of the new compounds on the MCF-7 breast cancer cells and ERα activation were investigated. All the steroids studied were synthesized starting from estrone methyl ether. The scaffold of compounds containing the six-membered ring D′ was constructed via the Diels–Alder reaction of butadiene with 3-methoxy-19-norpregna-1,3,5(10),16-tetraen-20-one 5. The hydrogenation of primary 16α,17α-cyclohexeno-adduct 7 followed by 3-demethylation (by HBr–AcOH) and reduction of 20-oxo group (by LiAlH4) or in one step by DIBAH gave target mono- and dihydroxy steroids 9–11. The Corey–Chaykovsky reaction of the same 3-methoxy-19-norpregna-1,3,5(10),16-tetraen-20-one 5 gave 16α,17α-methylene-substituted compound. The reaction of the latter with DIBAH immediately yielded 3,20-dihydroxy-16α,17α-methyleno-19-norpregna-1,3,5(10)-triene 13. The same procedures using 3-methoxy-19-norpregna-1,3,5(10),16-tetraen-20-one 5 produced corresponding 3,20-dihydroxy-16,17-19-norpregna-1,3,5(10)-triene 16 and 3,20-dihydroxy-19-norpregna-1,3,5(10),16-tetraene 17. All compounds were fully characterized by 1D and 2D NMR, HRMS, and X-ray diffraction. The molecular docking showed that the target compounds can bind to ER, their binding mode being similar to that of natural estradiol. 16α,17α-Methylene- or unsubstituted compounds exhibit the highest cytotoxicity against MCF-7 cells, being simultaneously relatively weak ERα inhibitors. 3,20-Dihydroxy steroids containing the six-membered ring D′ proved to be the most effective ERα inhibitors. These compounds displayed moderate cytotoxicity comparable of that of tamoxifen and showed no toxic effect on MCF-10A normal, nontumorigenic epithelial cells. The new ER antagonists were found to be good candidates for further testing as agents for the treatment and prevention of ERα-positive breast cancers.

Anti-addition of Dimethylsulfoxonium Methylide to Acyclic α,β-Unsaturated Ketones and Its Application in Formal Synthesis of an Eicosanoid.

Cyclopropanation using dimethylsulfoxonium methylide (Corey–Chaykovsky reaction) was examined with a series of linear α,β-unsaturated ketones, and the results showed that the major trajectory for the addition of the sulfur ylide to the enones is anti, related to the γ-substituent. The stereochemical assignment for the generated cyclopropanes was achieved by X-ray crystallography or comparing with the reported spectroscopic data. We found that the diastereoselectivity was influenced by several factors, including the protecting groups, solvents, and temperatures, and good anti/syn ratios (>10:1) were often obtained using the tert-butyldimethylsilyl and tert-butyldiphenylsilyl-protected substrates. The method was applied to a formal synthesis of a natural eicosanoid with good efficiency.

Corey-Chaykovsky Reactions of Nitro Styrenes Enable cis-Configured Trifluoromethyl Cyclopropanes.

Trifluoromethyl-substituted cyclopropanes are an attractive family of building blocks for the construction of pharmaceutical and agrochemical agents. This work demonstrated the utilization of fluorinated sulfur ylides as versatile reagents for Corey-Chaykovsky cyclopropanation reactions of nitro styrenes. This protocol favored the synthesis of cis-configured trifluoromethyl cyclopropanes for a broad range of substrates with excellent yields and good diastereoselectivities.

Chemical Synthesis of d-glycero-d-manno-Heptose 1,7-Bisphosphate and Evaluation of Its Ability to Modulate NF-κB Activation.

d-glycero-d-manno-Heptose 1,7-bisphosphate (HBP) is the precursor for heptose residues found in Gram-negative bacterial membrane surface glycoproteins and glycolipids. HBP β-anomer was recently reported to be a pathogen-associated molecular pattern (PAMP) that regulates TIFA-dependent immunity. Herein, we report the chemical synthesis of HBP α- and β-anomers, which highlights a C-7 carbon homologation via the Corey-Chaykovsky reaction, and the introduction of a phosphate group at the anomeric position using the Mitsunobu reaction. Furthermore, NF-κB reporter assaying revealed that HBP β-anomer activates the NF-κB signaling pathway.

ChemInform Abstract: Formal [4 + 1] Annulation of α‐Arylhydrazonoketones and Dimethylsulfoxonium Methylide: One‐Pot Synthesis of Substituted Pyrazoles and Dihydropyrazoles.

A formal [4 + 1] annulation of readily available α-arylhydrazonoketones and trimethylsulfoxonium iodide in the presence of cesium carbonate is described involving a sequential Corey–Chaykovsky reaction and intramolecular nucleophilic cyclization process. Substituted pyrazoles were obtained exclusively from the reactions of α-arylhydrazono-β-oxo-amides and trimethylsulfoxonium iodide in moderate to good yields, whereas the reactions of α-arylhydrazono-β-oxo-ketone/α-arylhydrazono- β-oxo-ester afforded the corresponding dihydropyrazoles in good yields.

ChemInform Abstract: (Thiolan‐2‐yl)diphenylmethyl Benzyl Ether/N,N′‐Diarylurea Cocatalyzed Asymmetric Aziridination of Cinnamyl Bromide and Aryl Aldimine

Abstract15 examples

Formal [4 + 1] Annulation of α-Arylhydrazonoketones and Dimethylsulfoxonium Methylide: One-pot Synthesis of Substituted Pyrazoles and Dihydropyrazoles.

A formal [4 + 1] annulation of readily available α-arylhydrazonoketones and trimethylsulfoxonium iodide in the presence of cesium carbonate is described involving a sequential Corey-Chaykovsky reaction and intramolecular nucleophilic cyclization process. Substituted pyrazoles were obtained exclusively from the reactions of α-arylhydrazono-β-oxo-amides and trimethylsulfoxonium iodide in moderate to good yields, whereas the reactions of α-arylhydrazono-β-oxo-ketone/α-arylhydrazono- β-oxo-ester afforded the corresponding dihydropyrazoles in good yields.

ChemInform Abstract: Organocatalytic [4 + 1]‐Annulation Approach for the Synthesis of Densely Functionalized Pyrazolidine Carboxylates.

AbstractA cascade reaction of α‐amination/Wittig olefination and either Corey—Chaykovsky reaction or intramolecular Michael addition reaction in presence of L‐proline provides access to functionalized pyrazolidines in a highly enantio‐ and diastereoselective fashion.

ChemInform Abstract: A Convenient Synthesis of Phebalosin: First Total Synthesis of Murraxocin.

AbstractThe Corey—Chaykovsky reaction of aldehyde (I) and sulfonium salt (II) is the key step in the synthesis of phebalosin (III).

Novel synthesis of 2H-1,5-benzoxathiepin-3(4H)-one and 5H-4,1-benzoxathiepin-3(2H)-one derivatives and chemical properties evaluation

New methods for the synthesis of 2H-1,5-benzoxathiepin-3(4H)-one and 5H-4,1-benzoxathiepin-3(2H)-one derivatives have been developed. Carbonyl group of 2H-1,5-benzoxathiepin-3(4H)-one has been protected by cyclic and acyclic ketals. Interaction of 2H-1,5-benzoxathiepin-3(4H)-one with NaBH4, hydroxylamine, hydrazines, and Br2 has been investigated. Strecker reaction has been carried out for the synthesis of corresponding α-amino acid. Combination of Horner–Wadsworth–Emmons and Michael reactions allowed to obtain derivatives of β-substituted carboxylic acid. Also, 2H-1,5-benzoxathiepin-3(4H)-one have been involved in Johnson–Corey–Chaykovsky reaction.

A convenient synthesis of phebalosin: first total synthesis of murraxocin

A convenient and high yielding total synthesis of phebalosin (1) has been achieved in four linear steps from commercially available umbelliferone. The first total synthesis of murraxocin (4), a natural product isolated from Murraya exotica has been described via phebalosin. Total syntheses of murrangatin (2) and murralongin (5) have also been demonstrated using the same strategy. The key step involves a Corey–Chaykovsky reaction to construct the isopreneepoxide unit.

(Thiolan-2-yl)diphenylmethyl benzyl ether/N,N′-diarylurea cocatalyzed asymmetric aziridination of cinnamyl bromide and aryl aldimine

A dual catalyst system using THT-based chiral sulfide 2a and H-bond donor 10a was developed for the asymmetric imino Corey–Chaykovsky reaction. Under the optimum reaction conditions, cinnamyl bromide reacted with a wide scope of N-diphenylphosphinic aldimines, to give the major trans-aryl cinnamyl aziridines with up to 98% ee. The role of H-bond donor 10a was demonstrated empirically as well.