Synthesis of Withasomnines and Their Non-natural Analogues from Aldehydes and 4-Nitro-1-butanol in Three Steps

Verma, Deepti; Kumar, Rahul; Namboothiri, Irishi N. N.

doi:10.1021/jo400207u

Cited by 23 publications

(5 citation statements)

References 28 publications

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“…In order to reduce the synthetic effort, we decided to use TMSCHN 2 as the 1,3‐dipole instead of diazosulfone (Scheme , Method B). The one‐pot two‐step process involves the 1,3‐dipolar cycloaddition and the intramolecular cyclization affording the Withasomnine 71 in 23% overall yield . Although the cycloaddition requires four days, the one‐pot methodology makes this approach (Scheme , Method B) very convenient and economical.…”

Section: Synthesis Of Withasomnine and Its Analogs By 13‐dipolar Cycmentioning

confidence: 99%

“…Various substituted α ‐bromopropyl nitroalkenes 82 were synthesized, and subsequent one‐pot 1,3‐dipolar cycloaddition with TMSCHN 2 and intramolecular cyclization furnished other natural Withasomnine alkaloids 83a and 83b in 25% and 18% overall yield respectively. The same strategy was further utilized to synthesize non‐natural Withasomnine analogs 83c‐e (Scheme ) …”

Section: Synthesis Of Withasomnine and Its Analogs By 13‐dipolar Cycmentioning

confidence: 99%

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Synthesis of Functionalized Pyrazoles via 1,3‐Dipolar Cycloaddition of α‐Diazo‐β‐ketophosphonates, Sufones and Esters with Electron‐Deficient Alkenes

Baiju

Namboothiri

2017

The Chemical Record

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1,3-Dipolar cycloaddition of diazo compounds with olefinic substrates is a promising atom-economic strategy for the construction of functionalized pyrazoles. Over the last few years, our group has been engaged in the synthesis of phosphonyl/sulfonylpyrazoles and pyrazole esters by employing Bestmann-Ohira Reagent (BOR) and its sulfur and ester analogs as 1,3-dipole precursors with various dipolarophiles. This account describes the novel synthetic methods developed in our laboratory, in the perspective of closely related work by others, for the synthesis of phosphonyl/sulfonylpyrazoles, pyrazole esters and the total synthesis of Withasomnine, a natural product, by using 1,3-dipolar cycloaddition as the key step.

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Section: Synthesis Of Withasomnine and Its Analogs By 13‐dipolar Cycmentioning

confidence: 99%

Section: Synthesis Of Withasomnine and Its Analogs By 13‐dipolar Cycmentioning

confidence: 99%

Synthesis of Functionalized Pyrazoles via 1,3‐Dipolar Cycloaddition of α‐Diazo‐β‐ketophosphonates, Sufones and Esters with Electron‐Deficient Alkenes

Baiju

Namboothiri

2017

The Chemical Record

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“…Namboothiri group has reported the total synthesis of three pyrazole containing withasomnine based alkaloids (Varma et al, 2013). Starting with 4-nitro-1-butanol and commercially available aldehydes, they synthesized these molecules in overall five steps.…”

Section: Chemistrymentioning

confidence: 99%

Chemistry and pharmacology of withania somnifera: An update

Kumar¹,

Dey²,

Hadimani³

et al. 2015

TANG [HUMANITAS MEDICINE]

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Withania somnifera (Ashwagandha) is an important Rasayana herb and widely considered as Indian ginseng in Ayurveda. In traditional system of Indian medicine, it is used as tonic to rejuvenate the body and increase longevity. In Ayurvedic preparations, various parts of the plant have been used to treat variety of ailments that affect the human health. However, dried roots of the plant are widely used for the treatment of nervous and sexual disorders. The major active chemical constituents of this plant are withanolides, which is responsible for its wide range of biological activities. Since the beginning of the 20 th century, a significant amount of research has been done and efforts are ongoing to further explore other bioactive constituents, and many pharmacological studies have been carried out to describe their disease preventing mechanisms. In this chapter, we have reviewed the chemistry and pharmacological basis of W. somnifera in various human ailments.

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“…Bromo compound 232 was prepared in two steps from 4-nitro-1-butanol 230 via Henry condensation, followed by conversion of the OH group to Br using CBr 4 and Ph 3 P. An overall yield of 39% was obtained for Ar ¼ Ph from the corresponding nitroalcohol 230. 156 Very recently, an efficient route for regioselective synthesis of pyrazoles 235 was developed by Zou group via reaction of a nitroallylic acetate 164 and N-tosyl hydrazine 234 in methanol for 30 min, followed by addition of Na 2 CO 3 (10 mol%) and reuxing the mixture for 2 h at 65 C (Scheme 78). 157 Aromatic, heteroaromatic and aliphatic nitroallylic acetates are compatible with this protocol to provide high to excellent yields of the products.…”

Section: And Benzene Ring In 127bmentioning

confidence: 99%

Part I: Nitroalkenes in the synthesis of heterocyclic compounds

2014

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The applications of nitroalkenes in the synthesis of three-to five-membered O, N and S-heterocycles, including natural products are investigated in this review. These heterocyclic compounds were synthesized from nitroalkenes with a variety of substituents at the a and b-positions and those that were part of common and medium rings via a wide variety of reactions such as Michael addition reactions, epoxidation, [3 + 2] cycloaddition and many cascade/domino/tandem reactions. In addition, the potential of nitroalkenes to take part in multi-component and cascade reactions, particularly, in diastereo-and enantioselective versions is reviewed. The high reactivity of nitroalkenes and their potential to coordinate with the metal catalysts as well as organocatalysts signify them as efficient precursors in synthetic organic chemistry. Also, the flexibility of the nitro group in functional group manipulations has expanded the scope of the nitro group, in general, and nitroalkenes, in particular, in organic synthesis.

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Synthesis of Withasomnines and Their Non-natural Analogues from Aldehydes and 4-Nitro-1-butanol in Three Steps

Cited by 23 publications

References 28 publications

Synthesis of Functionalized Pyrazoles via 1,3‐Dipolar Cycloaddition of α‐Diazo‐β‐ketophosphonates, Sufones and Esters with Electron‐Deficient Alkenes

Synthesis of Functionalized Pyrazoles via 1,3‐Dipolar Cycloaddition of α‐Diazo‐β‐ketophosphonates, Sufones and Esters with Electron‐Deficient Alkenes

Chemistry and pharmacology of withania somnifera: An update

Part I: Nitroalkenes in the synthesis of heterocyclic compounds

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