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9 results on '"Allylic Substitution-Reactions"'

1. Evolution in heterodonor P-N, P-S and P-O chiral ligands for preparing efficient catalysts for asymmetric catalysis. From design to applications

Author

Universitat Rovira i Virgili, Margalef, Jessica; Biosca, Maria; de la Cruz Sanchez, Pol; Faiges, Jorge; Pamies, Oscar; Dieguez, Montserrat, Universitat Rovira i Virgili, and Margalef, Jessica; Biosca, Maria; de la Cruz Sanchez, Pol; Faiges, Jorge; Pamies, Oscar; Dieguez, Montserrat

Abstract

The success of phosphine-oxazoline ligands (PHOX) inspired the progress in P-oxazoline ligand families by modifying either the ligand backbone, the electronic and/or steric properties of the phosphine group or by exchanging the phosphine to a phosphinite or a phosphite group. In this respect, the structures of chiral P-oxazoline ligands have become more diverse and new families of very efficient ligands have emerged, which have improved catalytic performance in some asymmetric transformations, with an increased versatility, both in the range of reactions and in the range of substrates/reagents. In addition, most of ligands are synthesized from easily accessible chiral amino alcohols, maintaining the short and efficient synthetic route developed for PHOX ligands. New ligands have been developed by replacing the oxazoline functionality with several other N-donor groups, e.g. imidazole, thiazole, oxazole, pyridine, etc., and O- and S-groups. This review offers a critical overview of the utility of these most successful bidentate heterodonor P-N, P-O and P-S ligand families applied in metal-mediated processes. We illustrate how, through proper ligand design, these heterodonor bidentate ligand families can be an excellent source of ligands, with superior catalytic performance in many asymmetric reactions than the best C-2-symmetric N,N and P,P-ligands reported so far. (C) 2021 The Authors. Published by Elsevier B.V.

Published
2021

2. Rhodium Catalyzed Asymmetric Hydroamination of Internal Alkynes with Indoline: Mechanism, Origin of Enantioselectivity, and Role of Additives

Author

C. Athira, Avtar Changotra, and Raghavan B. Sunoj

Subjects
TERMINAL ALKYNES, Carboxylic acid, chemistry.chemical_element, Alkyne, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, Catalysis, Rhodium, TRANS INFLUENCE, SET MODEL CHEMISTRY, ALKENE ISOMERIZATION, chemistry.chemical_compound, TOTAL ENERGIES, BETA-AMINO ACIDS, Hydrometalation, ALLYLIC SUBSTITUTION-REACTIONS, CH/PI INTERACTION, chemistry.chemical_classification, 010405 organic chemistry, organic chemicals, BITE ANGLE, Organic Chemistry, Oxidative addition, 0104 chemical sciences, BOND FORMATION, Dicarboxylic acid, chemistry, Hydroamination
Abstract

A comprehensive mechanistic study on the title reaction by using DFT(B3LYP-D3) computational method is reported. Explicit consideration of mono- (m-xylylic) and dicarboxylic acid (phthalic) in the key transition states reveals active participation of the carboxylic acid, beginning with the generation of a monomeric Rh(I) active catalyst and in the ensuing catalytic steps. In the early catalytic event, uptake of alkyne is predicted to take place only after the oxidative addition of the Rh(I) active catalyst to the carboxylic acid. The hydrometalation of the alkyne bound to the Rh(III)-H intermediate then generates a Rh(III)-vinyl intermediate, which in turn converts to a Rh(III)-allyl species. The inclusion of m-xylylic acid results in a two-step pathway to Rh(III)-allyl species via Rh-allene intermediate. A number of weak noncovalent interactions (hydrogen bonding and C-H center dot center dot center dot pi) between the catalyst and the substrates and that involving m-xylylic acid are found to have a direct impact on the regiochemical preference toward the branched product and the enantiocontrolling hydroamination step involving C-N bond formation leading to the major enantiomer (S-allylic amine). The chiral induction is enabled by cumulative effect of noncovalent interactions, which is an insight that could aid future developments of chiral ligands for asymmetric hydroamination.

Published
2018

3. Stereospecific Ring Contraction of Bromocycloheptenes through Dyotropic Rearrangements via Nonclassical Carbocation-Anion Pairs

Author

K. N. Houk, Shermin S. Goh, Makoto Fujita, Sureshbabu Guduguntla, Ben L. Feringa, Takashi Kikuchi, Pier Alexandre Champagne, Synthetic Organic Chemistry, and ​Basic and Translational Research and Imaging Methodology Development in Groningen (BRIDGE)

Subjects
BETA-LACTONES, inorganic chemicals, Contraction (grammar), Stereochemistry, CYCLOPROPYLCARBINYL, BUTYROLACTONES, Carbocation, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, Ion, Colloid and Surface Chemistry, Stereospecificity, GRIGNARD-REAGENTS, CONJUGATE ADDITION, ALLYLIC SUBSTITUTION-REACTIONS, ENANTIOSELECTIVE SYNTHESIS, Reaction conditions, Activation barrier, 010405 organic chemistry, Chemistry, ALLYLCARBINYL DERIVATIVES, Communication, Enantioselective synthesis, INTERCONVERSION REACTIONS, General Chemistry, 0104 chemical sciences, Lewis acid catalysis, SYMMETRY CONTROLLED REACTIONS, Chemical Sciences
Abstract

Experimental and theoretical evidence is reported for a rare type I dyotropic rearrangement involving a [1,2]-alkene shift, leading to the regio- and stereospecific ring contraction of bromocycloheptenes. This reaction occurs under mild conditions, with or without a Lewis acid catalyst. DFT calculations show that the reaction proceeds through a nonclassical carbocation-anion pair, which is crucial for the low activation barrier and enantiospecificity. The chiral cyclopropylcarbinyl cation may be a transition state or an intermediate, depending on the reaction conditions.

Published
2018

4. Catalytic Enantioselective Synthesis of Vicinal Dialkyl Arrays

Author

Ben L. Feringa, Anthoni W. van Zijl, Ferrnando Lopez, Wiktor Szymanski, Adriaan J. Minnaard, Stratingh Institute of Chemistry, Synthetic Organic Chemistry, Biotechnology, and Chemical Biology 2

Subjects
LASIUS-MERIDIONALIS, Ketone, Alkylation, Stereochemistry, Molecular Conformation, Chemical synthesis, Catalysis, Pheromones, Tsuji–Trost reaction, Animals, Sulfhydryl Compounds, GRIGNARD-REAGENTS, ALLYLIC SUBSTITUTION-REACTIONS, chemistry.chemical_classification, Aldehydes, Addition reaction, PHARAOHS ANT, Ants, Chemistry, Organic Chemistry, Enantioselective synthesis, Esters, Stereoisomerism, TRAIL PHEROMONE, Ketones, ASYMMETRIC CONJUGATE ADDITION, OLEFIN CROSS-METATHESIS, STEREOSELECTIVE-SYNTHESIS, Alcohols, Stereoselectivity, MYCOBACTERIUM-TUBERCULOSIS, MANDIBULAR GLAND SECRETION, Copper, Vicinal
Abstract

With a consecutive "asymmetric allylic alkylation (AAA)/cross-metathesis (CM)/conjugate addition (CA)" protocol it is possible to synthesize either stereoisomer of compounds containing a vicinal dialkyl array with excellent stereoselectivity. The versatility of this protocol in natural product synthesis is demonstrated in the preparation of the ant pheromones faranal and lasiol.

Published
2008

5. Large-bite bisphosphite, 1,3-C(6)H(4){OPOC(10)H(6)(mu-S)C(10)H(6)O}(2): Synthesis, copper(I), and gold(I) complexes

Author

Maravanji S. Balakrishna, Joel T. Mague, Benudhar Punji, and Pawan Kumar

Subjects
Cu(I) And Au(I) Complexes, Allylic Substitution-Reactions, Stereochemistry, Crystal Structures, chemistry.chemical_element, Crystal structure, Biochemistry, Catalysis, Coordination complex, Thioether-Phosphinite Ligands, Inorganic Chemistry, chemistry.chemical_compound, Bisphosphites, Materials Chemistry, Physical and Theoretical Chemistry, Pauson-Khand Reaction, Metal Chemistry, Triethylamine, chemistry.chemical_classification, P,N Ligands, Chemistry, Ligand, Organic Chemistry, Asymmetric hydrogenation, Mesocyclic Thioether, Coordination Polymers, Copper, Crystallography, Coordination Chemistry, Asymmetric Hydrogenation, Palladium(Ii) Complexes, Aurophilic Interactions, Single crystal, Donor
Abstract

Large-bite bisphosphite ligand 1,3-C(6)H(4){OPOC(10)H(6)(mu-S)C(10)H(6)O}(2) (3), is obtained by reacting chlorophosphonite {OC(10)H(6)(mu-S)C(10)H(6)O}PCl (2) with resorcinol in the presence of triethylamine. Treatment of 3 with CuCl in 1:1 molar ratio produces a 1D-coordination polymer [CuCl{(-OC(10)H(6)(mu-S)C(10)H(6)O-) P(-OC(6)H(4)O-)P(-OC(10)H(6)(mu-S)C(10)H(6)O-)}-kappa P,kappa P](infinity) (4) in good yield. Similar reaction of 3 with two equivalents of AuCl(SMe(2)) affords a dinuclear complex, [Au(2)Cl(2){(-OC(10)H(6)(mu-S)C(10)H(6)O-) P(-OC(6)H(4)O-)P(-OC(10)H(6)(mu-S)C(10)H(6)O-)}-kappa P,kappa P] (5). Single crystal X-ray structures of the ligand 3 and the complexes 4 and 5 are reported. The gold complex 5 shows dimeric structure supported by strong Au center dot center dot center dot Au aurophilic interactions. (C) 2009 Elsevier B. V. .

Published
2010

6. Group 11 metal complexes of the mesocyclic thioether aminophosphonites [-OC10H6(mu-S)C10H6O-]PNC4H8E (E = O, NMe)

Author

PUNJI, B, MAGUE, JT, and BALAKRISHNA, MS

Subjects
Coordination Chemistry, Asymmetric Hydrogenation, Allylic Substitution-Reactions, Palladium Complex, Sulfur Donor Action, Ps Ligands Copper, Gold, Pauson-Khand Reaction, Molecular-Structures, Reversible Conversion, Cross-Coupling Reactions, Structural-Characterization, Thioether-Aminophosphonites
Abstract

Group 11 metal complexes of the mesocyclic thioether aminophosphonites [-OC10H6(mu-S)C10H6O-]PNC4H8E {2a: E = O; 2b: E = NMe; IUPAC names: 4-(dinaphtho[2,1-d:1',2'-g][1,3,6,2]dioxathiaphosphocin-4-yl)morpholine (2a), 1-(dinaphtho[2,1-d:1',2'-gl[1,3,6,2]dioxathiaphosphocin-4-yl)- 4-methylpiperazine (2b)} are reported. Thioether aminophosphonites 2a and 2b react with CuX (X = Cl, Br, and I) in a 1:1 molar ratio to give the tricoordinate, dimeric complexes [{[{-OC10H6(mu-S)C10H6O-}PNC4H8E-kappa P]Cu(mu-X)}(2)] (4a: E = O, X = Cl; 4b: E NMe, X = Cl; 5a: E = O, X = Br; 5b: E = NMe, X = Br; 6a: E = O, X = I; 6b: E = NMe, X = I), whereas with 2:1 molar ratios monomeric complexes of the type [{[-OC10H6(mu-S)C10H6O-]PNC4H8O-kappa P)(2)CUX] (7a: E = O, X = Cl; 7b: E = NMe, X = Cl; 8a: E = O, X = Br; 8b: E = NMe, X = Br; 9a: E = O, X = I; 9b: E = NMe, X = I) are obtained in excellent yield. The PS-chelated cationic complexes [{[-OC10H6(mu-S)C10H6O-]PNC4H8E-kappa P,kappa S](2)Cu]BF4 (10a: E = O; 10b: E = We) are obtained when 2a and 2b are treated with half an equivalent of [(MeCN)(4)Cu]BF4. Similarly, the silver complexes [{[{-OC10H6(mu-S)C10H6O-}PNC4H8E-kappa P,kappa S]-AgCF3SO3}(2)] (11a: E = O: 11b: E = NMe) and [{[-OC10H6(mu-S)C10H6O-]PNC4H8E-kappa P,kappa S)Ag(PPh3)]CF3SO3 (12a: E = O; 12b: E = NMe) are synthesized by the treatment of thioether aminophosphonites 2a and 2b with AgOTf and [Ag(PPh3)][OTf], respectively. Reactions of 2a and 2b with [AuCl(SMe2)] produce the simple monomeric gold(I) complexes [{[-OC10H6(mu-S)C10H6O-]PNC4H8E-kappa P)AuCl] (13a: E = O; 13b: E = NMe). The iodo derivatives [{[-OC10H6(mu-S)C10H6O-]PNC4H8E-kappa P)AuI] (14a: E = O; 14b: E = NMe) are obtained by the halide-exchange reaction of 13a and 13b with CuI at room temperature. The structures of complexes 5a, 7a, 8a, 13a, 13b, and 14a are confirmed by single-crystal X-ray diffraction studies. In all of these complexes, the sulfur atom in the mesocyclic ring shows coordinative interaction towards the phosphorus atom, and in 5a, 7a, 8a, and 14a towards the metal center as well.

Published
2007

7. Adaptative Biaryl Phosphite-Oxazole and Phosphite-Thiazole Ligands for Asymmetric Ir-Catalyzed Hydrogenation of Alkenes

Author

Química Física i Inorgànica, Universitat Rovira i Virgili, Dieguez, Montserrat, Andersson, Pher G., Pamies, Oscar, Paptchikhine, Alexander, Mazuela, Javier, Química Física i Inorgànica, Universitat Rovira i Virgili, Dieguez, Montserrat, Andersson, Pher G., Pamies, Oscar, Paptchikhine, Alexander, and Mazuela, Javier

Abstract

A library of readily available phosphite-oxazole/thiazole ligands (L1 a-g-L7 a-g) was applied in the Ir-catalyzed asymmetric hydrogenation of several largely unfunctionalized E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridge length, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/configurations in the biaryl phosphite moiety), so that enantioselectivities could he maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (cc) values up to >99%) or a wide range of E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility.

Published
2010

8. Rh-Catalyzed Asymmetric Hydroformylation of Heterocyclic Olefins Using Chiral Diphosphite Ligands. Scope and Limitations

Author

Química Física i Inorgànica, Universitat Rovira i Virgili, Dieguez, Montserrat, Pamies, Oscar, Coll, Mercedes, Mazuela, Javier, Química Física i Inorgànica, Universitat Rovira i Virgili, Dieguez, Montserrat, Pamies, Oscar, Coll, Mercedes, and Mazuela, Javier

Abstract

We used a series of diphosphite ligands to study the effect of the ligand backbone, the length of the bridge, and the substituents of the biphenyl moieties and determine the scope of this type of ligand in the Rh-catalyzed asymmetric hydroformylation of several hetereocylic olefins. By carefully selecting the ligand components, we achieved high chemo-, regio-, and enantioselectivities in different substrate types. Unprecedentedly high enantioselectivities for five-membered heterocyclic olefins were therefore obtained. Note that both enantiomers of the hydroformylation products can be synthesized using the same ligand by a simple substrate change. For the seven-membered heterocyclic dioxepines, our results are among the best obtained. Also, both enantiomers of the hydroformylation products can be obtained by using pseudoenantiomer ligands or by carefully tuning the ligand parameters.

Published
2009

9. Screening of a modular sugar-based phosphite-oxazoline ligand library in asymmetric Pd-catalyzed heck reactions

Author

Química Física i Inorgànica, Universitat Rovira i Virgili, Dieguez, Montserrat, Pamies, Oscar, Mata, Yvette, Química Física i Inorgànica, Universitat Rovira i Virgili, Dieguez, Montserrat, Pamies, Oscar, and Mata, Yvette

Abstract

We have synthesised a library of phosphite-oxazoline ligands derived from readily available D-glucosamine. These ligands have been successfully screened in the palladium-catalysed Heck reaction of several substrates with high regio- (up to 99%) and enantioselectivities (ee's up to 99%) as well as with improved activities under standard thermal conditions. The results indicate that the catalytic performance is highly affected by the oxazoline and biarylphosphite substituents and the axial chirality of the biaryl moiety of the ligand. The Heck reactions were also performed under microwave irradiation conditions, allowing a considerably shorter reaction time (full conversion in minutes) maintaining the excellent regio- and enantioselectivities.

Published
2007

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