Synthetic Approaches to Crinipellin Based Tetraquinanes via Ring‐Rearrangement Metathesis and Ring‐Closing Metathesis

Keesari

2021

J. Org. Chem.

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We describe a modular approach to angularly fused polyquinanes that are core units of many natural products such as cameroonanol, subergorgic acid, and crinepellin, etc. in excellent yields by employing atom-economic ring-rearrangement metathesis as a key step. Our work highlights, the synthesis of cameroonanol analogues 1–6 and their ester derivatives by using the stereoselective reduction of the carbonyl group by using DIBAL-H- and DCC-mediated coupling as the key reactions. The subergorgic acid core 7 was produced by LDA-mediated kinetically controlled regio- and stereoselective ring-junction allylation as a critical step. Moreover, it is worth mentioning that the present strategy relies on a less explored exo-dicyclopentadiene-1-one (8) and produces highly congested polycyclic frameworks containing up to seven contiguous stereogenic centers including quaternary carbons up to two. All of the new molecules were characterized by NMR data. The structure and relative stereochemistry of some compounds were confirmed by chemical methods and further supported by single-crystal X-ray diffraction studies. The newly reported tri- and tetraquinane skeletons are present in many naturally occurring bioactive polyquinanes. Hence, this strategy is useful for designing various “druglike molecules” and expands the chemical space of cyclopentanoids that are useful in medicinal chemistry.

Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

“…II. General Procedure for Olefin-Metathesis Reaction: Synthesis of Compounds 7,12,13,[16][17][18][19][20]22,23,29,30,41,42,47,48,66,and 69. Method A (RRM/ROM).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 2 more Smart Citations

A Modular Approach to Angularly Fused Polyquinanes via Ring-Rearrangement Metathesis: Synthetic Access to Cameroonanol Analogues and the Basic Core of Subergorgic Acid and Crinipellin

Keesari

2021

J. Org. Chem.

Self Cite

“…Similarly, the triallyl derivative 83 undergo the RRM sequence in the presence of G‐II catalyst to produce tetraquinane 87 (Scheme 9). [9f] …”

Section: Model Studies and Total Synthesis Of Crinipellinmentioning

confidence: 99%

Synthetic Approaches to Natural and Unnatural Tetraquinanes

Fatma

2021

Asian J Org Chem

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Design and Synthesis of Highly Decorated Oxa‐Cage Systems via Olefin Metathesis

Keesari

2022

Asian J Org Chem

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Here, we report diversely fused oxa‐cages starting from various alkyl‐substituted cyclic‐ether derivatives derived via intramolecular cyclocetherification of endo‐alcohol containing endo‐norbornene derivatives. All these higher oxa‐cage systems are assembled in good to excellent yield by employing ring‐closing metathesis (RCM) or ring‐opening metathesis (ROM) as a key step. Ru‐based Grubbs catalysts (G‐I, G‐II) are effective to assemble these target molecules. In addition, a highly strained bicyclo[2.2.1]hepatane system fused oxa‐cages are easily prepared by hydrogenation sequence. Also, several highly fused saturated oxa‐cage derivatives are reported. A total of 22 examples are reported and all of these compounds are well‐characterized by NMR and HRMS data. The target compounds reported here may find significant applications in various fields of chemistry.