Synthesis of Aza-polyquinanes via Fischer Indolization and Ring-Rearrangement Metathesis as Key Steps

Kotha, Sambasivarao; Keesari, Ramakrishna Reddy; Ansari, Saima

doi:10.1055/s-0039-1690179

Cited by 18 publications

(10 citation statements)

References 7 publications

(7 reference statements)

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“…The compound 5 can be prepared from exo-DCPD-1-one by following the known literature procedure. [30] To create highly functionalized linear triquinanes, we first focused on the preparation of key intermediate 4 in a substantial amount. For this purpose, base-mediated regio-and stereoselective mono-allylation at the α-position of compound 5 was attempted to produce the requisite α-monoallyl derivative 4 (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Design and Synthesis of Linearly Fused Triquinanes through Tandem‐Metathesis: Access to Basic Core of Cucumin, Capnellene, Chondrosterin, and Xeromphalinone

Kotha

Keesari

2023

Eur J Org Chem

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Herein, a short synthetic approach to linearly fused tricyclic enone 1 and cis‐anti‐cis type hydroxy‐triquinane 2 has been described in an efficient manner by employing tandem‐metathesis as a key step. The triquinane‐based enone 1 is prepared by a Babler–Dauben oxidation of hydroxy‐triquinane 2, which is assembled by following a three‐step sequence involving a regio‐ and stereoselective allylation, vinyl Grignard addition, and tandem‐metathesis. Our strategy relies on exo‐tricyclic ketone, which is derived from readily available exo‐dicyclopentadiene‐1‐one. The newly synthesized molecules were identified and characterized by nuclear magnetic resonance spectroscopy (NMR), and high‐resolution mass spectrometry (HRMS) data. It is worth mentioning that tricyclic enone 1 is present as a core unit of many naturally occurring polyquinanes, particularly xeromphalinone family members. Hence, our approach may be useful in the synthesis of such bioactive molecules.

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Section: Resultsmentioning

confidence: 99%

Design and Synthesis of Linearly Fused Triquinanes through Tandem‐Metathesis: Access to Basic Core of Cucumin, Capnellene, Chondrosterin, and Xeromphalinone

Kotha

Keesari

2023

Eur J Org Chem

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“…[29] Whereas, the ring-closure between A&C and A'&C' olefinic moieties are not feasible due to the unfavourable exo-ring-junction stereochemistry. [30] Furthermore, to gain a better insight into metathetic behaviour between A&C and A'&C' olefinic moieties, we selected several 1,4-addition products 4, 18 and 19 which are derived from exo-dicyclopentadiene-1-one (5) (Scheme 6). [31] When compounds 4, 18 and 19 were treated with different Grubbs catalysts under diverse reaction conditions (Scheme 7; Table 2), RRM products 20 a-22 a were not produced even when the long-chain alkenyls are present.…”

Section: Resultsmentioning

confidence: 99%

“…In this context, it is worth mentioning that among cis ‐, and trans ‐isomers of bicyclo[3.3.0]octane (Figure 8b), trans ‐isomer is 6.4 kcal/mol more strained than the cis ‐isomer [29] . Whereas, the ring‐closure between A & C and A′ & C′ olefinic moieties are not feasible due to the unfavourable exo ‐ring‐junction stereochemistry [30] …”

Section: Resultsmentioning

confidence: 99%

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

Kotha

Keesari

2021

Asian J Org Chem

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Herein, we have studied the synthetic approaches to tetraquinanes that are present in crinipellin type natural products by employing ring-rearrangement metathesis (RRM) and ring-closing metathesis (RCM) as key steps. These studies involve finding the suitable alkylation sequence to prepare desired RRM/RCM precursors. Methyl-tetraquinane has been assembled by employing a regio-, and stereoselective methylation followed by allylation sequence. Whereas, allyltetraquinane was constructed by following the allylation-RRM sequence. Interestingly, spiro-quinanes rearranges to fusedquinanes when olefinic moiety is present adjacent to the spiro-ring under RRM conditions. Additionally, several di-, and triquinane derivatives reported during this study were also found in diverse polyquinane natural products. The present strategy utilizes the vinyl derivative of exo-dicyclopentadiene-1-one, and produce several intricate polycyclic systems. Our strategy may be useful to design various medicinally important "drug-like" molecules.

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“…Very recently, Kotha et al used a sequence of Fischer indole synthesis, N-allylation, and ring rearrangement metathesis for the synthesis of azapolyquinanes. 72…”

Section: Account Syn Lettmentioning

confidence: 99%

Adventures and Detours in the Synthesis of Hydropentalenes

Deimling

Zens

Park

et al. 2020

Synlett

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Functionalized hydropentalenes (i.e., bicyclo[3.3.0]octanones) constitute important building blocks for natural products and for ligands for asymmetric catalysis. The assembly and tailored functionalization of this convex roof-shaped scaffold is challenging and has motivated a variety of synthetic approaches including our own contributions, which will be presented in this account.1 Introduction2 Biosynthesis of Hydropentalenes3 Hydropentalenes through the Pauson–Khand Reaction4 Hydropentalenes through Transannular Oxidative Cyclization of Cycloocta-1,4-diene5 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Dodecahydrocyclopenta[a]indenes6 Functionalization of Bicyclo[3.3.0]octan-1,4-diones to Crown Ether Hybrids7 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Cylindramide8 Tandem Ring-Opening Metathesis/Ring-Closing Metathesis/Cross-Metathesis of Bicyclo[2.2.1]heptanes9 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Geodin A10 Hydropentalenes through Enantioselective Desymmetrization of Weiss Diketones11 Functionalization of Weiss Diketones by Carbonyl Ene Reactions12 Functionalization of the Weiss Diketone to Cylindramide and Geodin A Core Units13 Biological Properties of Bicyclo[3.3.0]octanes14 Hydropentalenes through Vinylcyclopropane Cyclopentene Rearrangement15 Functionalization of Bicyclo[3.3.0]octanes toward Chiral Dienes16 Miscellaneous Syntheses of Hydropentalenes17 Conclusion and Outlook

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Synthesis of Aza-polyquinanes via Fischer Indolization and Ring-Rearrangement Metathesis as Key Steps

Cited by 18 publications

References 7 publications

Design and Synthesis of Linearly Fused Triquinanes through Tandem‐Metathesis: Access to Basic Core of Cucumin, Capnellene, Chondrosterin, and Xeromphalinone

Design and Synthesis of Linearly Fused Triquinanes through Tandem‐Metathesis: Access to Basic Core of Cucumin, Capnellene, Chondrosterin, and Xeromphalinone

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

Adventures and Detours in the Synthesis of Hydropentalenes

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