nBu3P-Catalyzed Desulfonylative [3 + 2] Cycloadditions of Allylic Carbonates with Arylazosulfones to Pyrazole Derivatives

Zhang, Qi; Meng, Ling‐Guo; Wang, Kuai; Wang, Lei

doi:10.1021/ol503735c

Cited by 63 publications

(26 citation statements)

References 55 publications

(21 reference statements)

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“…Although electron-deficient alkenes and imines have been extensively used as substrates in phosphane-catalyzed ylide [3 + 2] annulations, the analogous diazenes have been scarcely explored. Only recently have Wang and co-workers [10] successfully developed phosphane-catalyzed desulfonylative [3 + 2] annulation between MBH carbonates 1 and arylazosulfones 37. Pyrazole derivatives 38 were afforded in good to excellent yields with a broad range of substrates (Scheme 13).…”

Section: Intermolecular [3 + 2] Annulationsmentioning

confidence: 99%

Advances in Annulation Reactions Initiated by Phosphorus Ylides Generated in situ

Zhou

2016

Eur J Org Chem

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Over the past two decades, the rapid development of nucleophilic phosphane catalysis has transported phosphorus ylide chemistry into an area beyond olefination. Phosphorus ylides generated in situ on nucleophilic addition of phosphanes to electrophilic unsaturated species, followed by some necessary proton-transfer steps, have effected many powerful annulation reactions to construct carbo-and heterocycles

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Section: Intermolecular [3 + 2] Annulationsmentioning

confidence: 99%

Advances in Annulation Reactions Initiated by Phosphorus Ylides Generated in situ

Zhou

2016

Eur J Org Chem

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“…33 Three-component reaction in 0.5 g of each of these three DESs at room temperature have resulted in the Schiff bases and benzylidenemalononitriles as the major products (Entries 7, 9, 11), pyrazoles were obtained in 35-40% yields due to the increase of temperature to 80 °C (Entries 8, 10, 12). One-pot twostep process was screened according to route b. Two-step procedure was carried out in all DESs, the increase in molar ratios of glycerol reduced the product yield (Entries [13][14][15][16][17][18]. This can be caused by the higher pH of DES1.…”

Section: Chemistrymentioning

confidence: 99%

“…The first stage reaction did not proceed completely at room temperature or at higher temperature even after 8 h, due to the lack of appearance of the intermediary benzylidenemalononitriles in the reaction media. Therefore, the next stage reaction of unconsumed reagents especially aldehydes with hydrazine was inevitable under these conditions (Entries 13,15,17). Adding water to achieve the final DES1/H 2 O ratios of 1:2, 1:1 and 3:1 (w:w) has improved reaction time and product yield, the condensation reaction of malononitrile with aldehyde 113.67-117.37 ppm.…”

Section: Chemistrymentioning

confidence: 99%

“…13 Various methods were proposed for the synthesis of pyrazole and their analogues. [14][15][16][17] In this regard, a solution of the appropriate triethylamine in 1,4-dioxane efficiently catalysed synthesis of pyridine, thiophene and 4H-pyrane Similar procedures were designed to prepare pyrazole derivatives. [19][20][21][22][23][24] Most of these methods include simultaneous or multistep reaction of aldehyde, hydrazine and active methylene compounds under different conditions.…”

Section: Introductionmentioning

confidence: 99%

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Green One-pot Synthesis of Novel Polysubstituted Pyrazole Derivatives as Potential Antimicrobial Agents

Beyzaei

Motraghi

Aryan

et al. 2017

ACSi

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Various biological properties of natural and synthetic pyrazole derivatives such as anti-inflammatory, antimicrobial, neuroprotective, anticonvulsant, antidepressant and anticancer activities encouraged us to propose a new, fast, green and eco-friendly procedure for the preparation of some novel 5-amino-3-(aryl substituted)-1-(2,4-dinitrophenyl)-1H-pyrazole-4-carbonitriles. They were efficiently synthesized via one-pot two-step process reaction of malononitrile, 2,4-dinitrophenylhydrazine and different benzaldehydes in deep eutectic solvent (DES) glycerol/potassium carbonate. The products yield and reaction times were considerably improved in the presence of applied DES. Antibacterial effects of all newly synthesized pyrazoles in comparison with several common antibiotics were evaluated against a variety of Gram-positive and Gram-negative pathogenic bacteria. In addition to, their inhibitory activities on three fungi were compared to some current antifungal agents. The moderate to good antimicrobial potentials particularly against fungi were observed in the major heterocyclic compounds according to the IZD, MIC, MBC and MFC results.

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“…In addition to allenoates, alkenyl and alkynyl ketones, Morita–Baylis–Hillman (MBH) carbonates have recently been used in organocatalysis for the formation of CC or CX (X = N or O) bonds (Equations i and j depicted in Scheme C) in experiment . In this kind of reaction, the phosphine catalysts nucleophilic attack to MBH carbonates affording phosphonium enolate zwitterions, which can then serve as a three‐synthon to participate in [3 + 3] and other kinds of annulations.…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigation toward organophosphine‐catalyzed [3 + 3] annulation of Morita–Baylis–Hillman carbonates with azomethine imines: Mechanism, origin of stereoselectivity, and role of catalyst

Zhang

Qiao

Wang

et al. 2017

Int J of Quantum Chemistry

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A computational study on the detailed mechanism and stereoselectivity of the chiral phosphinecatalyzed C(sp 2 )AH activation/[3 1 3] annulation between Morita-Baylis-Hillman (MBH) carbonates and C,N-cyclic azomethine imines has been performed. Generally, the catalytic cycle consists of two stages, that is, C(sp 2 )AH activation companied by the dissociation of the t-BuOCO 2 2 group forming phosphonium enolate, and [3 1 3] cycloaddition process followed by regeneration of the catalyst. The calculated results indicate that C(sp 2 )AH activation is ratedetermining while [3 1 3] cycloaddition is stereoselectivity-determining. Furthermore, the advantageous hydrogen bond interactions and less steric hindrance in the RR configurational CAC bond forming transition states should be responsible for the favorability of RR-configured product among the four possible products. The special role of the organocatalyst was also identified by natural bond orbital (NBO) and global reactivity index (GRI) analyses. The mechanistic insights obtained in the present study should be useful for understanding the novel organocatalytic C (sp 2 )AH activation and cycloaddition cascade reaction of MBH carbonates, and thus provide valuable clues on rational design of efficient organocatalysts for the C(sp 2 )AH activation/ functionalizations. K E Y W O R D S [3 1 3] cycloaddition, DFT, organophosphine catalysis, stereoselectivity Int J Quantum Chem. 2017;117:e25367.

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ⁿBu₃P-Catalyzed Desulfonylative [3 + 2] Cycloadditions of Allylic Carbonates with Arylazosulfones to Pyrazole Derivatives

Cited by 63 publications

References 55 publications

Advances in Annulation Reactions Initiated by Phosphorus Ylides Generated in situ

Advances in Annulation Reactions Initiated by Phosphorus Ylides Generated in situ

Green One-pot Synthesis of Novel Polysubstituted Pyrazole Derivatives as Potential Antimicrobial Agents

Theoretical investigation toward organophosphine‐catalyzed [3 + 3] annulation of Morita–Baylis–Hillman carbonates with azomethine imines: Mechanism, origin of stereoselectivity, and role of catalyst

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