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“Friedelane triterpenoids: transformations toward A-ring modifications including 2-homoderivatives”


Abstract: Friedelin and its derivatives, commonly known as friedelane triterpenoids exhibit potential biological effects ranging from antimicrobial to anticancer to anti-HIV. In urge to modify the A-ring of the pentacyclic triterpenoid, various transformative scopes had been utilized. Herein, some simple unprecedented transformative protocols have been accomplished towards furnishing altogether 42 (25 new) A-ring modified pentacyclic friedelane triterpenoids. Of note, the modifications include the all-new 2-homoderivatives. One-pot BF3.OEt2-mediated oxidative transformation of friedelin to yield friedel-3-enol acetate as the major product was one of the key reactions. A group of isomeric A-ring modifications were then resulted on the basis of simple transformations on suitable friedelane-based molecules. The syntheses of the novel 2-homofriedelanes were envisioned on the basis of the transformative reactions of the designed triterpenoid 3-chlorofriedel-2-ene-2-carbaldehyde which was isolated as the major product from the reaction of friedelin with the novel Vilsmeyer-Haack reagent. A-ring modified new derivatives are also due to further interesting transformations of 3-chlorofriedel-3-ene, isolated as a side product from the same reaction. Again, considering the scope of 3-chloro-2-enal moiety, associated with the A-ring of the triterpenoid, some heterocycle-linked- (bonded to C3) 2-homofriedelane triterpenoids were synthesized. Thus, various common reaction strategies were employed on suitable substrates to achieve finally a series of C2,C3-; C3,C4-; and C2,C3,C4- functionalized as well as 2-homofriedelane triterpenoids just within one to four efficient steps.

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Publication details

The article was received on 01 Jan 2018, accepted on 05 Mar 2018 and first published on 06 Mar 2018

Article type: Paper
DOI: 10.1039/C8NJ00009C
Citation: New J. Chem., 2018, Accepted Manuscript
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    “Friedelane triterpenoids: transformations toward A-ring modifications including 2-homoderivatives”

    P. Ghosh, J. Das and A. Sarkar, New J. Chem., 2018, Accepted Manuscript , DOI: 10.1039/C8NJ00009C

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