Total synthesis of (±)-<i>epi</i>-stemodan-13α,17-diol

Chen, Song; Chen, Ting; Liu, Guanggen; Wang, Xiao; Zhu, Guili; Liu, Yongjiang; Fu, Shaomin; Liu, Bo

doi:10.1039/c9ob00661c

Cited by 9 publications

(4 citation statements)

References 53 publications

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“…By our protocol, precursor polyenes 7 was synthesized from 1‐iodo‐2‐methoxybenzene, n Pr‐ Ge and homogeranyl iodide [28] 3 u in one step (Scheme 2). Following TiCl 4 ‐mediated polycyclization [29] and demethylation by BBr 3 was able to give n Pr analog of Totarol 8 in 41 % yield. The NMR data of analog 8 is consistent with reported literature [27] .…”

Section: Methodsmentioning

confidence: 99%

Alkylation‐Terminated Catellani Reactions Using Alkyl Carbagermatranes

Jiang

Yang

et al. 2020

Angewandte Chemie

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The Catellani reaction has received substantial attention because it enables rapid multiple derivatization on aromatics. While using alkyl electrophiles to achieve orthoalkylation was one of the earliest applications of the Catellani reaction, ipso-alkylation-terminated reactions with b-H-containing reactants has not been realized to date. Herein, we report alkylation-terminated Catellani reaction using alkyl carbagermatranes (abbreviated as alkyl-Ge) as nucleophiles. The reactivity of alkyl-Ge and alkyl-B(OH) 2 in this reaction is discussed. This approach enables efficient dialkylation with b-H-containing reactants, which was previously inaccessible by Catellani reactions. Scheme 1. Alkyl nucleophiles in Catellani reactions. NBE = norbornene.

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Section: Methodsmentioning

confidence: 99%

Alkylation‐Terminated Catellani Reactions Using Alkyl Carbagermatranes

Jiang

Yang

et al. 2020

Angewandte Chemie

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“…Stemodan‐13α,17‐diol (13α‐ 342 ) is a tetracyclic stemodane‐type diterpenoid isolated form Stemodia chilensis . Liu and co‐workers [ 117 ] achieved the synthesis of stemodan‐13β,17‐diol ( 342 ) employing polyene cyclization strategy (Scheme 40). Alkylation of 334 with geranyl bromide ( 333 ) followed by polyene cyclization in presence of TiCl 4 delivered tricyclic compound 335 .…”

Section: Miscellaneous Approaches In Pgf Total Synthesis Of Naturamentioning

confidence: 99%

Evolution of Strategies in Protecting‐Group‐Free Synthesis of Natural Products: A Recent Update

2020

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The synthesis of complex natural products must be realized with high economy and efficiency, contributing largely to sustainable development in synthetic organic chemistry. The new strategies should adopt protecting‐group‐free approaches enabling step‐economy and thereby enhancing efficiency. Various approaches based on chiral pool, auxiliary‐based methods, cascade, biomimetic, enzymatic and photocatalytic used in total synthesis of natural products and following the PGF‐criteria over the last two years (2018–2019) have been reviewed here. These should guide sustainable synthesis of natural products in the future.

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“…Recently, we have successfully developed an efficient strategy achieving complex polycyclic core skeletons via iron-promoted intramolecular perezone-type [5 + 2] cycloaddition . Then total synthesis of a derivative of stemodane-type diterpenoid, stemodan-13α,17-diol, was completed by us with such a [5 + 2] cycloaddition as the key reaction . Thus, we envisioned that andilesin C ( 3 ) could also be achieved through this methodology.…”

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confidence: 99%

“…It is worth noting that the reaction temperature should be maintained at −5 °C so as to minimize the formation of isomers and p -benzoquinone byproduct. Then the benzoquinone 10 was subjected to our developed iron-promoted intramolecular [5 + 2] cycloaddition conditions to achieve the desired cycloadduct 16 . , Compound 16 underwent demethylation in the presence of BBr 3 to afford the enol 17 . Subsequently, conversion to an enol triflate, followed by palladium-catalyzed methoxycarbonylation reaction, afforded the β-keto ester 18 .…”

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confidence: 99%

Construction of BCDEF Core of Andilesin C

et al. 2019

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A synthetic study toward the BCDEF core skeleton of andilesin C is presented. Key elements involved iron-promoted intramolecular perezone-type [5 + 2] cycloaddition to install the BCD ring system simultaneously in a one-step, copper-catalyzed intramolecular cyclopropanation followed by BiCl3-promoted retro-aldol reaction to construct ring E and a one-pot manipulation involving reduction, lactonization, and isomerization to introduce the lactone ring F. We finally synthesized the congested BCDEF ring system of andilesin C, featuring four quaternary centers and two tertiary centers, by following a strategy with a 15-pot reaction and 11 purification operations.

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Total synthesis of (±)-epi-stemodan-13α,17-diol

Abstract: Stemodan-13α,17-diol is a natural stemodane-type diterpenoid isolated from Stemodia chilensis.

Cited by 9 publications

References 53 publications

Alkylation‐Terminated Catellani Reactions Using Alkyl Carbagermatranes

Alkylation‐Terminated Catellani Reactions Using Alkyl Carbagermatranes

Evolution of Strategies in Protecting‐Group‐Free Synthesis of Natural Products: A Recent Update

Construction of BCDEF Core of Andilesin C

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