An efficient [3+2] cycloaddition for the synthesis of substituted pyrazolo[1,5-c]quinazolines

Wang, Tao; Shao, Ailong; Feng, Hao; Yang, Shuwu; Gao, Meng; Tian, Jun; Lei, Aiwen

doi:10.1016/j.tet.2015.03.019

Cited by 20 publications

(7 citation statements)

References 27 publications

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“…In recent years, more efficient accesses to pyrazolo[1,5- c ]quinazolines by [3 + 2] cycloaddition reaction have been established. In these reactions, the stepwise or concerted [3 + 2] cycloaddition reactions of N -iminoquinazolinium ylides with electron-deficient alkenes, 3-diazoindolin-2-ones with activated alkynes, or enaminones are the most step-economical strategies. Alternatively, such scaffolds can also be obtained by similar [3 + 2] cycloaddition reactions of 3-ylideneoxindoles with diazomethane derivatives …”

Section: Introductionmentioning

confidence: 99%

The Practical Access to Fluoroalkylated Pyrazolo[1,5-c]quinazolines by Fluoroalkyl-Promoted [3 + 2] Cycloaddition Reaction

et al. 2023

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The efficient synthesis of fluoroalkylated pyrazolo[1,5-c]quinazolines by reactions of 3-diazoindolin-2-ones with methyl β-fluoroalkylpropionates has been achieved. This protocol affords two regioisomers of fluoroalkylated pyrazolo[1,5c]quinazolines with excellent yields in total. The dipolarophilicity of methyl β-fluoroalkylpropionates enhanced by perfluoroalkyl groups is crucial for the high efficiency of this [3 + 2] cycloaddition reaction.

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Section: Introductionmentioning

confidence: 99%

The Practical Access to Fluoroalkylated Pyrazolo[1,5-c]quinazolines by Fluoroalkyl-Promoted [3 + 2] Cycloaddition Reaction

et al. 2023

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“…Remarkably, organocatalytic and metal‐catalyzed methods have displayed outstanding regioselectivities and chemical yields [24–26] . Similarly, other dipoles have been explored in [3+2] cyclization reactions forging different classes of heterocycles, including cyanopyrazoles, [27] isoxazoles, [28] and pyrazolo[1,5‐c]quinazolines [29] . These reactions have in common the elimination of HNO 2 furnishing the five‐membered aromatic heterocyclic after the cycloaddition step.…”

Section: Introductionmentioning

confidence: 99%

“…[24][25][26] Similarly, other dipoles have been explored in [3 + 2] cyclization reactions forging different classes of heterocycles, including cyanopyrazoles, [27] isoxazoles, [28] and pyrazolo [1,5-c]quinazolines. [29] These reactions have in common the elimination of HNO 2 furnishing the five-membered aromatic heterocyclic after the cycloaddition step. Experimental and computational studies have been applied to the mechanisms of Huisgen azide-alkyne cycloadditions, along with "click" copper [30,31] ruthenium catalyzed [13] and strain-promoted versions.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Aspects on [3+2] Cycloaddition (32CA) Reactions of Azides to Nitroolefins: A Computational and Kinetic Study

Kawamura

Alegre‐Requena

Barbosa

et al. 2022

Chemistry A European J

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3 + 2] cycloadditions of nitroolefins have emerged as a selective and catalyst-free alternative for the synthesis of 1,2,3-triazoles from azides. We describe mechanistic studies into the cycloaddition/rearomatization reaction sequence. DFT calculations revealed a rate-limiting cycloaddition step proceeding via an asynchronous TS with high kinetic selectivity for the 1,5-triazole. Kinetic studies reveal a secondorder rate law, and 13 C kinetic isotopic effects at natural abundance were measured with a significant normal effect at the conjugated olefinic centers of 1.0158 and 1.0216 at the α and β-carbons of β-nitrostyrene. Distortion/interaction-activa-tion strain and energy decomposition analyses revealed that the major regioisomeric pathway benefits from an earlier and less-distorted TS, while intermolecular interaction terms dominate the preference for 1,5-over 1,4-cycloadducts. In addition, the major regioisomer also has more favorable electrostatic and dispersion terms. Additionally, while static DFT calculations suggest a concerted but highly asynchronous Ei-type HNO 2 elimination mechanism, quasiclassical direct-dynamics calculations reveal the existence of a dynamic intermediate.

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“…These kinds of building blocks were first reported by Lei in 2015, which can be used as 1,3-dipoles in [3 + 2] dipolar cycloaddition for the preparation of pyrazolo [1,5c]quinazoline derivatives (Scheme 1a, top left). 1 Since then, they have been widely used to synthesize structurally diverse N-heterocyclic compounds. Because of the intrinsic properties of 1,3-dipoles, their reactions mainly focused on [3 + n] cycloadditions to produce various angular polycyclic aromatic molecules (Scheme 1a).…”

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confidence: 99%

Sequential Dearomatization/Rearrangement of Quinazoline-Derived Azomethine Imines for the Synthesis of Nitrogen-Rich Three-Dimensional Cage-Like Molecules

Wang,

Yang,

Wang

et al. 2024

Org. Lett.

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A sequential dearomatization/rearrangement reaction between quinazoline-derived azomethine imines and crotonate sulfonium salts has been developed to provide a series of threedimensional cage-like molecules. The reaction involves two dearomatizations, two cyclizations, and two C−C bond and three C−N bond formations in one step. The new transformation has a broad substrate scope, does not require any added reagents, and proceeds under room temperature in a short time. A mechanistic rationale for the sequential dearomatization/rearrangement is also presented. Furthermore, the synthetic compounds are evaluated for their glucose control effect. Compounds 3aa and 3aj were found to be hyperglycemic, which might be lead compounds for treating hypoglycemia.

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An efficient [3+2] cycloaddition for the synthesis of substituted pyrazolo[1,5-c]quinazolines

Cited by 20 publications

References 27 publications

The Practical Access to Fluoroalkylated Pyrazolo[1,5-c]quinazolines by Fluoroalkyl-Promoted [3 + 2] Cycloaddition Reaction

The Practical Access to Fluoroalkylated Pyrazolo[1,5-c]quinazolines by Fluoroalkyl-Promoted [3 + 2] Cycloaddition Reaction

Mechanistic Aspects on [3+2] Cycloaddition (32CA) Reactions of Azides to Nitroolefins: A Computational and Kinetic Study

Sequential Dearomatization/Rearrangement of Quinazoline-Derived Azomethine Imines for the Synthesis of Nitrogen-Rich Three-Dimensional Cage-Like Molecules

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