Construction of C2-indolyl-quaternary centers by branch-selective allylation: enabling concise total synthesis of the (±)-mersicarpine alkaloid

Ghosh, Minakshi; Sahu, Samrat; Saha, Shuvendu; Maji, Modhu Sudan

doi:10.1039/d3sc04732f

Cited by 7 publications

(1 citation statement)

References 57 publications

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“…1 Among them, allylsilanes and allylboranes are distinguished by their facile manipulation and exceptional selectivity in various transformations. 1 e – i ,2 In this regard, (1-silyl)allylboranes, a particular class of allylic gem -dimetalloids possessing both silicon and boron functionalities at the same allylic carbon, are anticipated to serve as useful building blocks for the synthesis of complex molecules. 3 The high potential of (1-silyl)allylboranes has been empirically evidenced by the broad scope of transformations through regio-, chemo-, and stereoselective C–C bond forming reactions.…”

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Synthesis of (1-silyl)allylboronates by KOtBu-catalyzed ring-opening gem-silylborylation of cyclopropenes

Fujii,

Hirata,

Moniwa

et al. 2024

Chem. Commun.

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confidence: 99%

Synthesis of (1-silyl)allylboronates by KOtBu-catalyzed ring-opening gem-silylborylation of cyclopropenes

Fujii,

Hirata,

Moniwa

et al. 2024

Chem. Commun.

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Asymmetric 1,2‐Migration at Vicinal Tetrasubstituted Stereocenters Constructed from α‐Keto Imines

Karan,

Sahu,

Metya

et al. 2024

Angewandte Chemie

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A carbonyl‐assisted asymmetric 1,2‐migratory allylation through in situ generation of vicinal tetrasubstituted stereocenters is reported to access enantiopure α‐amino ketones, and amino‐alcohols with excellent yields and diastereoselectivities. In a remarkable divergence, despite having higher steric hindrance, the allylation exclusively occurs on ketones over imines in the first step, followed by a face‐selective 1,2‐allyl transfer, thus highlighting an exciting interplay between two distinct electrophiles. The methodology distinguishes itself through its adaptability to gram‐scale synthesis, showcasing broad functional group tolerance, and stereodivergence. The density functional theory (DFT) analysis elucidates a deeper understanding of its selectivity and mechanistic framework. Highlighting its transformative potential, the total synthesis of hapalindole alkaloids were adeptly achieved.

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Direct Asymmetric Synthesis of α‐Aminoimines from 1,2‐Bis‐N‐Sulfinylimines by Using Allyl Boronic Acids

Bhunia,

Karan,

Snehil

et al. 2024

Angewandte Chemie

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A unique direct asymmetric synthesis of α‐aminoimines is realized, through rapid and exclusive mono‐allylation of chiral bis‐N‐sulfinylimines using allylboronic acids. The highly selective allylation was possible as electrophilic imine functional group in the product α‐aminoimines remained unreactive towards allyl boronic acid nucleophiles. Notably, by varying the geometry and chiral auxiliary, all four isomers of the α‐aminoimines were accessed from readily available precursors. A range of allyl nucleophiles, which are tricky to generate by other means possessing highly reactive functional groups also took part in this reaction, expanding the scope further. The applicability of the products α‐aminoimines were further demonstrated by accessing a range of structurally diverse chiral cyclic and acyclic 1,2‐diamines bearing adjacent stereocenters through addition of a second nucleophile or aza‐Prins‐type cyclization by exploiting the nucleophilicity of the tethered alkene moiety. Moreover, the leaving group aptitude of sulfinyl auxiliary attached to imine, was exploited to access valuable chiral α‐aminonitriles under thermal conditions without employing any reagents. Detailed DFT calculation revealed a chair‐like transition state likely operating for the allylboration reaction across imine.

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Construction of C2-indolyl-quaternary centers by branch-selective allylation: enabling concise total synthesis of the (±)-mersicarpine alkaloid

Abstract: Herein we report a branch-selective allylation strategy for accessing C2-indolyl-all-carbon quaternary centers using allylboronic acids. This approach boasts broad functional group tolerance, scalability, and relies on easily accessible allyl alcohol...

Cited by 7 publications

References 57 publications

Synthesis of (1-silyl)allylboronates by KOtBu-catalyzed ring-opening gem-silylborylation of cyclopropenes

Synthesis of (1-silyl)allylboronates by KOtBu-catalyzed ring-opening gem-silylborylation of cyclopropenes

Asymmetric 1,2‐Migration at Vicinal Tetrasubstituted Stereocenters Constructed from α‐Keto Imines

Direct Asymmetric Synthesis of α‐Aminoimines from 1,2‐Bis‐N‐Sulfinylimines by Using Allyl Boronic Acids

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