Expeditious synthesis of N-bridged heterocycles via dipolar cycloaddition of pentafulvenes with 3-oxidopyridinium betaines

Kuthanapillil, Jinesh M.; Thulasi, Sreeja; Rajan, Rani; Krishnan, Karthik; Suresh, Eringathodi; Radhakrishnan, K. V.

doi:10.1016/j.tet.2010.11.084

Cited by 14 publications

(9 citation statements)

References 81 publications

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“…The reaction of 1b -H with 6,6-dimethylfulvene ( 6b ) was conducted in a similar manner to afford 7bb along with an inseparable minor product in a 1.5:1 ratio. The spectral data for 7ba and 7bb were in good accordance with those previously reported …”

Section: Resultssupporting

confidence: 90%

“…Katritzky et al reported that the cycloaddition of betaine 1c with 6,6-dimethylfulvene as a 6π component at 20 °C in diethyl ether afforded the (5 + 6) cycloadduct in 31% yield . Later, Radhakrishnan et al reported the cycloaddition of betaines 1b and 1c with various pentafulvenes in tetrahydrofuran (THF) between 0 °C and room temperature over 6 h, and the yields were significantly improved (63–72%) . We also revisited the cycloaddition of 1b with pentafulvenes.…”

Section: Resultsmentioning

confidence: 52%

“…We investigated 1-(2-pyrimidyl)-3-oxidopyridinium ( 1b ) as a model betaine instead of the 4,6-dimethylpyrimidyl-substituted analogue used by the Katritzky group to eliminate the steric influence of the methyl groups on the pyrimidyl moiety . The cycloaddition of 1b with pentafulvenes was reported by Radhakrishnan and co-workers . The oxidopyridinium moieties of 1a – c have similar structural parameters, as shown in Figure a.…”

Section: Resultsmentioning

confidence: 94%

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Oxidopyridinium Cycloadditions Revisited: A Combined Computational and Experimental Study on the Reactivity of 1-(2-Pyrimidyl)-3-oxidopyridinium Betaine

et al. 2023

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To investigate the effect of N-substituents on their reactivity and selectivity of oxidopyridinium betaines, we performed density functional theory (DFT) calculations of model cycloadditions with N-methylmaleimide and acenaphthylene. The theoretically expected results were compared with the experimental results. Subsequently, we demonstrated that 1-(2pyrimidyl)-3-oxidopyridinium can be used for (5 + 2) cycloadditions with various electron-deficient alkenes, dimethyl acetylenedicarboxylate, acenaphthylene, and styrene. In addition, a DFT analysis of the cycloaddition of 1-(2-pyrimidyl)-3oxidopyridinium with 6,6-dimethylpentafulvene suggested the possibility of pathway bifurcations involving a (5 + 4)/(5 + 6) ambimodal transition state, although only (5 + 6) cycloadducts were experimentally observed. A related (5 + 4) cycloaddition was observed in the reaction of 1-(2-pyrimidyl)-3-oxidopyridinium with 2,3-dimethylbut-1,3-diene.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 94%

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Oxidopyridinium Cycloadditions Revisited: A Combined Computational and Experimental Study on the Reactivity of 1-(2-Pyrimidyl)-3-oxidopyridinium Betaine

et al. 2023

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“…Inspired by the versatile cycloaddition profile of pentafulvenes with 3-oxidopyrylium betaines, our group recently undertook the cycloaddition of pentafulvenes with 3-oxidopyridinium betaines, afforded either by the action of a base on the pyridinium salt or thermally from pyridinium betaine dimer . The methodology furnished an extremely versatile approach toward the synthesis of bicyclo[6.3.0]undecanes 238 and bicyclo[5.3.0]decanes 239 via [6+3] and [3+2] cycloaddition reactions of pentafulvenes with 3-oxidopyridinium betaines 236 (Scheme ).…”

Section: Cycloaddition Chemistry Of Pentafulvenesmentioning

confidence: 99%

Recent Advances in the Chemistry of Pentafulvenes

et al. 2017

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Pentafulvenes are a unique class of compounds that originally attracted attention due to their propensity to display nonbenzenoid aromaticity. Subsequently, they were recognized as valuable synthons for the construction of a wide range of compounds by virtue of their ability to display multiple cycloaddition profiles. Naturally, this area of organic chemistry has experienced rapid growth over the last five decades, fueled by elegant work showcasing the unique reactivity of pentafulvenes in a plethora of cycloaddition reactions. In this Review, we have attempted to provide a systematic account of the methods for the generation of pentafulvenes, their rich and varied cycloaddition chemistry, organometallic reactions, and theoretical studies that support their versatility. Further, we have highlighted their applications in the synthesis of a variety of complex structural frameworks. It is our conviction that this Review will be useful to a wide range of chemists, and will spur further research in this promising area.

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“…Fulvenes are a class of highly reactive intermediates , with unusual electronic properties and two main applications, the creation of complex polycyclic frameworks through cycloaddition reactions − and the synthesis of substituted cyclopentadienyl derivatives via nucleophilic addition. ,− Despite the current interest in these reactions, little has changed in fulvene synthesis methods since Thiele first prepared them in 1900 via condensation of cyclopentadiene and an aldehyde or ketone in the presence of sodium ethanolate (Scheme ). A multistep synthesis was developed by Hafner in 1964, specifically targeting highly electrophilic aldehydes and even enabling the synthesis of the unsubstituted fulvene .…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of Pyrrolidine Buffer-Catalyzed Fulvene Formation

et al. 2018

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Rapid synthesis of fulvenes is achieved using pyrrolidinium/pyrrolidine buffers in anhydrous acetonitrile. Time-dependent UV−vis absorption and NMR spectroscopy reveal that the rate and yield of fulvene formation depend strongly on both the presence of acid in the medium and the choice of solvent, and they are negatively affected by water. Kinetic data have been collected for various substrates, and the synthetic benefits of the adjusted reaction conditions are showcased. Enhancements of reaction rates are found in comparison to literature procedures. α-Unsaturated fulvenes that were previously difficult to access can now be obtained in good yields.

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Expeditious synthesis of N-bridged heterocycles via dipolar cycloaddition of pentafulvenes with 3-oxidopyridinium betaines

Cited by 14 publications

References 81 publications

Oxidopyridinium Cycloadditions Revisited: A Combined Computational and Experimental Study on the Reactivity of 1-(2-Pyrimidyl)-3-oxidopyridinium Betaine

Oxidopyridinium Cycloadditions Revisited: A Combined Computational and Experimental Study on the Reactivity of 1-(2-Pyrimidyl)-3-oxidopyridinium Betaine

Recent Advances in the Chemistry of Pentafulvenes

Kinetics and Mechanism of Pyrrolidine Buffer-Catalyzed Fulvene Formation

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