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  • 1.
    Bunrit, Anon
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Stockholm University.
    Direct Catalytic Nucleophilic Substitution of Non-Derivatized Alcohols2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis focuses on the development of methods for the activation of the hydroxyl group in non-derivatized alcohols in substitution reactions. The thesis is divided into two parts, describing three different catalytic systems.

    The first part of the thesis (Chapter 2) describes nucleophilic allylation of amines with allylic alcohols, using a palladium catalyst to generate unsymmetrical diallylated amines. The corresponding amines were further transformed by a one-pot ring-closing metathesis and aromatization reaction to afford β-substituted pyrroles with linear and branched alkyl, benzyl, and aryl groups in overall moderate to good yields.

    The second part (Chapters 3 and 4) describes the direct intramolecular stereospecific nucleophilic substitution of the hydroxyl group in enantioenriched alcohols by Lewis acid and Brønsted acid/base catalysis.

    In Chapter 3, the direct intramolecular substitution of non-derivatized alcohols has been developed using Fe(OTf)3 as catalyst. The hydroxyl groups of aryl, allyl, and alkyl alcohols were substituted by the attack of O- and N-centered nucleophiles, to provide five- and six-membered heterocycles in up to excellent yields with high enantiospecificities. Experimental studies showed that the reaction follows first-order dependence with respect to the catalyst, the internal nucleophile, and the internal electrophile of the substrate. Competition and catalyst-substrate interaction experiments demonstrated that this transformation proceeds via an SN2-type reaction pathway.

    In Chapter 4, a Brønsted acid/base catalyzed intramolecular substitution of non-derivatized alcohols was developed. The direct intramolecular and stereospecific substitution of different alcohols was successfully catalyzed by phosphinic acid (H3PO2). The hydroxyl groups of aryl, allyl, propargyl, and alkyl alcohols were substituted by O-, N-, and S-centered nucleophiles to generate five- and six-membered heterocycles in good to excellent yields with high enantiospecificities. Mechanistic studies (both experiments and density functional theory calculations) have been performed on the reaction forming five-membered heterocyclic compounds. Experimental studies showed that phosphinic acid does not promote SN1 reactivity. Rate-order determination indicated that the reaction follows first-order dependence with respect to the catalyst, the internal nucleophile, and the internal electrophile. DFT calculations corroborated with a reaction pathway in which the phosphinic acid has a dual activation mode and operates as a bifunctional Brønsted acid/Brønsted base to simultaneously activate both the nucleophile and nucleofuge, resulting in a unique bridging transition state in an SN2-type reaction mechanism.

  • 2.
    Bunrit, Anon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Uppsala University, Sweden.
    Dahlstrand, Christian
    Srifa, Pemikar
    Olsson, Sandra K.
    Huang, Genping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Tianjin University, China.
    Biswas, Srijit
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Samec, Joseph S. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Uppsala University, Sweden.
    Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer2016Inngår i: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, Vol. 27, nr 2, s. 173-176Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A brief overview of the development of direct substitution of the hydroxyl (OH) group of alcohols in our research group is presented. By applying a BrOnsted acid, an intramolecular substitution of the OH group in stereogenic alcohols with chirality transfer was achieved. Noteworthy, the intramolecular substitution has a wide scope in respect to both the nucleophile and also the nucleofuge. A mechanistic study by both experiments and DFT calculations revealed a unique reaction pathway in which the BrOnsted acid operates in a bifunctional manner to promote an S(N)2-type reaction mechanism.

  • 3.
    Bunrit, Anon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Uppsala University, Sweden.
    Sawadjoon, Supaporn
    Tšupova, Svetlana
    Sjöberg, Per J. R.
    Samec, Joseph S. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Uppsala University, Sweden.
    A General Route to beta-Substituted Pyrroles by Transition-Metal Catalysis2016Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, nr 4, s. 1450-1460Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An atom-efficient route to pyrroles substituted in the beta-position has been achieved in four high yielding steps by a combination of Pd, Ru, and Fe catalysis with only water and ethene as side-products. The reaction is general and gives pyrroles substituted in the beta-position with linear and branched alkyl, benzyl, or aryl groups in overall good yields. The synthetic route includes a Pd-catalyzed monoallylation step of amines with substituted allylic alcohols that proceeds to yield the monoallylated products in moderate to excellent yields. In a second step, unsymmetrical diallylated aromatic amines are generated from the reaction of a second allylic alcohol with high selectivity in moderate to good yields by control of the reaction temperature. Ru-catalyzed ring-closing metathesis performed on the diallylated aromatic amines yields the pyrrolines substituted in the beta-position in excellent yields. By addition of ferric chloride to the reaction mixture, a selective aromatization to yield the corresponding pyrroles substituted in the beta-position was achieved. A reaction mechanism involving a palladium hydride, generated from insertion of palladium to O-H of an allyl alcohol, that is responsible for the C-O bond cleavage to generate the pi-allyl intermediate is proposed.

  • 4.
    Bunrit, Anon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Srifa, Pemikar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dahlstrand, Christian
    Huang, Genping
    Biswas, Srijit
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Watile, Rahul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Samec, Joseph
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    H3PO2-Catalyzed Intramolecular Stereospecific Substitution of the Hydroxyl Group in Stereogenic Secondary Alcohols by N-, O-, and S-centered Nucleophiles to Generate HeterocyclesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The direct intramolecular stereospecific substitution of the hydroxyl group in stereogenic secondary alcohols was successfully accomplished by phosphinic acid catalysis. The hydroxyl group was displaced by O-, S-, and N-centered nucleophiles to provide enantioenriched five- and six-membered heterocycles in good to excellent yields and high enantiospecificity with water as the only by product. Mechanistic studies using both experiments and calculations have been performed. Rate order determination shows first-order dependences in catalyst, internal nucleophile, and electrophile concentrations, however, independence on external nucleophile and electrophile. Furthermore, phosphinic acid does not promote SN1 reactivity. Computational studies support a bifunctional role of the phosphinic acid in which activations of both nucleofuge and nucleophile occur in a bridging SN2-type transition state. 

  • 5.
    Bunrit, Anon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Watile, Rahul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lagerspets, Emi
    Lanekoff, Ingela
    Biswas, Srijit
    Repo, Timo
    Samec, Joseph
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Iron (III)-Catalyzed Intramolecular Stereospecific Substitution of the OH Group in Stereogenic Secondary and Tertiary AlcoholsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    We herein report a Fe(OTf)3-catalyzed stereospecific substitution of the hydroxyl (OH) group in secondary and tertiary alcohols by N-, and O-centered nucleophiles to generate synthetically precious enantioenriched pyrrolidines, tetrahydrofuran, 1,2,3,4-tetra-hydroquinolines, and chromanes. The substitution of the OH group in benzylic, allylic, and aliphatic alcohols proceed with high yields and high degree of enantiospecificity to give saturated five- and six-membered heterocyclic products and water as the only by-product. Mechanistic studies revealed that the intramolecular substitution reaction proceeds through an SN2 reaction with secondary alcohols and an SN1 reaction, comprising a tight ion pair, with tertiary alcohols giving products with inversion of configuration at the stereogenic carbon in both cases. The iron interacts with both nucleofile and nucloefuge, where the latter leads to a controlled carbon−oxygen (C–O) bond cleavage. The procedure opens up new atom efficient technique for catalytic stereospecific reactions that allow easily accessible stereogenic secondary and tertiary alcohols to be considered as substrates in substitution reactions. 

  • 6.
    Watile, Rahul A.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bunrit, Anon
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margalef, Jèssica
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Akkarasamiyo, Sunisa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ayub, Rabia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lagerspets, Emi
    Biswas, Srijit
    Repo, Timo
    Samec, Joseph S. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Intramolecular substitutions of secondary and tertiary alcohols with chirality transfer by an iron (III) catalyst2019Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, artikkel-id 3826Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optically pure alcohols are abundant in nature and attractive as feedstock for organic synthesis but challenging for further transformation using atom efficient and sustainable methodologies, particularly when there is a desire to conserve the chirality. Usually, substitution of the OH group of stereogenic alcohols with conservation of chirality requires derivatization as part of a complex, stoichiometric procedure. We herein demonstrate that a simple, inexpensive, and environmentally benign iron(III) catalyst promotes the direct intramolecular substitution of enantiomerically enriched secondary and tertiary alcohols with O-, N-, and S-centered nucleophiles to generate valuable 5-membered, 6-membered and aryl-fused 6-membered heterocyclic compounds with chirality transfer and water as the only byproduct. The power of the methodology is demonstrated in the total synthesis of (+)-lentiginosine from D-glucose where iron-catalysis is used in a key step. Adoption of this methodology will contribute towards the transition to sustainable and bio-based processes in the pharmaceutical and agrochemical industries.

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