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  • 1.
    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. 

  • 2.
    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. 

  • 3.
    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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