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Nuno Maulide - One of the best experts on this subject based on the ideXlab platform.

  • development of a reductive hosomi sakurai Reaction
    Tetrahedron, 2018
    Co-Authors: Adriano Bauer, Nuno Maulide
    Abstract:

    Abstract Herein we present a full account on the reductive Hosomi-Sakurai Reaction along with some insight into the Reaction mechanism. Stereoselectivity appears to be highest when the crucial carbocation intermediate, derived by protonation of the homoallylic ether, is sufficiently stabilized to ensure that the hydride transfer becomes rate-determining. This hypothesis is supported by experiment and mechanistic analysis.

  • a stereoselective reductive hosomi sakurai Reaction
    Organic Letters, 2018
    Co-Authors: Adriano Bauer, Nuno Maulide
    Abstract:

    A novel reductive variant of the classical Hosomi–Sakurai Reaction is reported. This transformation hinges on a redox-neutral, stereoselective internal reduction event under mild conditions. This operationally simple Reaction relies on readily available starting materials and leads to useful products in diastereoselectivities of up to 7:1. The versatility of this new method is demonstrated through the stereoselective one-step synthesis of an AChE inhibitor.

  • A Stereoselective Reductive Hosomi–Sakurai Reaction
    Organic Letters, 2018
    Co-Authors: Adriano Bauer, Nuno Maulide
    Abstract:

    A novel reductive variant of the classical Hosomi–Sakurai Reaction is reported. This transformation hinges on a redox-neutral, stereoselective internal reduction event under mild conditions. This operationally simple Reaction relies on readily available starting materials and leads to useful products in diastereoselectivities of up to 7:1. The versatility of this new method is demonstrated through the stereoselective one-step synthesis of an AChE inhibitor.

Jingping Zhang - One of the best experts on this subject based on the ideXlab platform.

Adriano Bauer - One of the best experts on this subject based on the ideXlab platform.

  • development of a reductive hosomi sakurai Reaction
    Tetrahedron, 2018
    Co-Authors: Adriano Bauer, Nuno Maulide
    Abstract:

    Abstract Herein we present a full account on the reductive Hosomi-Sakurai Reaction along with some insight into the Reaction mechanism. Stereoselectivity appears to be highest when the crucial carbocation intermediate, derived by protonation of the homoallylic ether, is sufficiently stabilized to ensure that the hydride transfer becomes rate-determining. This hypothesis is supported by experiment and mechanistic analysis.

  • a stereoselective reductive hosomi sakurai Reaction
    Organic Letters, 2018
    Co-Authors: Adriano Bauer, Nuno Maulide
    Abstract:

    A novel reductive variant of the classical Hosomi–Sakurai Reaction is reported. This transformation hinges on a redox-neutral, stereoselective internal reduction event under mild conditions. This operationally simple Reaction relies on readily available starting materials and leads to useful products in diastereoselectivities of up to 7:1. The versatility of this new method is demonstrated through the stereoselective one-step synthesis of an AChE inhibitor.

  • A Stereoselective Reductive Hosomi–Sakurai Reaction
    Organic Letters, 2018
    Co-Authors: Adriano Bauer, Nuno Maulide
    Abstract:

    A novel reductive variant of the classical Hosomi–Sakurai Reaction is reported. This transformation hinges on a redox-neutral, stereoselective internal reduction event under mild conditions. This operationally simple Reaction relies on readily available starting materials and leads to useful products in diastereoselectivities of up to 7:1. The versatility of this new method is demonstrated through the stereoselective one-step synthesis of an AChE inhibitor.

Amitabha Sarkar - One of the best experts on this subject based on the ideXlab platform.

  • high diastereoselectivity in hosomi sakurai Reaction on metal complexed acyclic enones role of out of plane coordination of lewis acid
    Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2001
    Co-Authors: Sunil K Mandal, Sambasivam Ganesh, Vedavati G. Puranik, Amitabha Sarkar
    Abstract:

    Efficient diastereocontrol is achieved in Hosomi-Sakurai Reaction of flexible acyclic enones anchored on arene­ tricarbonylchromium template. Relative stereochemistry of groups in the products is compared with those obtained by al­ lylmagnesium bromide addition followed by an anionic oxy-Cope rearrangement. The results indicate an endo-selective conjugate addition dictated by an out-of-plane bound Lewis acid in the Hosomi-Sakurai Reaction, similar to the trend estab­ lished earlier for rigid substrate structures. We recently reported I an unusual , endo-selective, conjugate allylation on 2-arylidene-1-tetralone tricar­ bonylchromium complex 2 by Hosomi-Sakurai reac­ tion 3 . In this stereochemically well-defined substrate, the expected in-plane coordination of Lewis acid to the ketone carbonyl group was thought to be pre­ vented by two flanking hydrogens, the peri proton of the aromatic ring of tetralone and the l3-olefinic pro­ ton, held in a rigid framework. As a result, the Lewis acid was forced to coordinate in an out-of-plane man­ ner from the more accessible exo face, which in tum blocked approach of reagent from the same face. The net effect was an endo-selective allylation (Scheme I). The same concept was subsequently ex­ ploited to predictably induce endo-selective nucleo­ philic additions of organolithium 4 and organomagne­ sium 5 reagents to such substrates in presence of Lewis acids. In flexible, acyclic analogues, a rotation about the C(O)-alkene bond leading to cisoid (I and II) or tran­ soid (III) orientation of the enone (Chart 1) can jeop­ ardize diastereoselectivity. It may be noted, however, that the steric inhibition offered by the flanking hy­ drogens in I or II (cisoid orientation) would still ad

  • stereodivergent c c bond formation on arene chromium template endo selective allylation by hosomi sakurai Reaction
    Journal of Organic Chemistry, 1996
    Co-Authors: Sambasivam Ganesh, Vedavati G. Puranik, Pinak Chakrabarti, Amitabha Sarkar
    Abstract:

    In arene-tricarbonylchromium complexes, excellent diastereocontrol at benzylic or homobenzylic sites can be achieved since the Cr(CO)3 group effectively blocks one face of the molecule and prevents approach of reagents from this direction.1 This feature has been widely utilized in designing useful synthetic strategies.2 Suitably structured substrates allow almost total diastereoselectivity even three carbons away from the complexed aromatic ring.3 In most of these instances, the Reaction occurs from the exo face, i.e., the face opposite to the metal; endo-selective Reactions are particularly rare.4 Herein we wish to report a completely endo-selective Hosomi-Sakurai allylation5 on the 2-arylidene-1-tetralone-Cr(CO)3 complex. The corresponding exo-adduct was obtained by an alternative sequence of Reactions. In addition to displaying an unusual stereochemical preference, the TiCl4-catalyzed allylation Reaction provides a prima facie evidence of out-of-plane coordination of titanium to the ketone dictating steric course of the Reaction.

  • Stereodivergent C-C Bond Formation on Arene-Chromium Template: Endo-Selective Allylation by Hosomi-Sakurai Reaction †
    Journal of Organic Chemistry, 1996
    Co-Authors: Sambasivam Ganesh, Vedavati G. Puranik, Pinak Chakrabarti, Amitabha Sarkar
    Abstract:

    In arene-tricarbonylchromium complexes, excellent diastereocontrol at benzylic or homobenzylic sites can be achieved since the Cr(CO)3 group effectively blocks one face of the molecule and prevents approach of reagents from this direction.1 This feature has been widely utilized in designing useful synthetic strategies.2 Suitably structured substrates allow almost total diastereoselectivity even three carbons away from the complexed aromatic ring.3 In most of these instances, the Reaction occurs from the exo face, i.e., the face opposite to the metal; endo-selective Reactions are particularly rare.4 Herein we wish to report a completely endo-selective Hosomi-Sakurai allylation5 on the 2-arylidene-1-tetralone-Cr(CO)3 complex. The corresponding exo-adduct was obtained by an alternative sequence of Reactions. In addition to displaying an unusual stereochemical preference, the TiCl4-catalyzed allylation Reaction provides a prima facie evidence of out-of-plane coordination of titanium to the ketone dictating steric course of the Reaction.

Guichun Fang - One of the best experts on this subject based on the ideXlab platform.