Catalytic Synthesis of Pyrano- and Furoquinolines Using Nano Silica Chromic Acid at Room Temperature

Ali Gharib,Manouchehr Jahangir

doi:10.1155/2013/693763

Ali Gharib, Manouchehr Jahangir

Open Access

https://doi.org/10.1155/2013/693763

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Abstract

Nano silica chromic acid (nano-SCA) is found to catalyze efficiently the three component-coupling reactions of aldehydes, amines, and cyclic enol ethers such as 3,4-dihydro-2H-pyran and 2,3-dihydrofuran under mild conditions to afford the corresponding pyrano- and furanoquinolines in excellent yields with high endoselectivity. Interestingly, 2,3-dihydrofuran afforded selectively endoproducts under the similar reaction conditions. Heterogeneous reaction conditions, easy procedure, short reaction time, and high yields are some important advantages of this method.

Highlights

Aza-Diels-Alder reactions rank among the most powerful methodologies for the construction of nitrogen-containing six-membered ring compounds [1]
The pyranoquinolines and furanoquinolines are a class of nitrogen-containing heterocycles which are synthesized by Aza-Diels-Alder methodology
A mixture of aldehyde (1 mmol), aryl amine (1 mmol), and 3,4-dihydro-2H-pyran or 2,3-dihydrofuran (2 mmol) in THF (10 mL), nano silica chromic acid (0.07 g) was added and the mixture stirred at room temperature for an appropriate time

Summary

Introduction

Aza-Diels-Alder reactions rank among the most powerful methodologies for the construction of nitrogen-containing six-membered ring compounds [1]. The pyranoquinolines and furanoquinolines are a class of nitrogen-containing heterocycles which are synthesized by Aza-Diels-Alder methodology. Pyranoquinoline derivatives are found to possess a wide spectrum of biological activities such as psychotropic, antiallergenic, anti-inflammatory, and estrogenic activity [7]. These compounds are prepared by Aza-DielsAlder reactions of imines derived from aldehydes and amines with dihydropyran or dihydrofuran. We wish to present a simple one-pot protocol for synthesis of pyrano[3,2-c]quinolines and furano quinolines using nano-SCA, benzaldehyde, aniline, and 3,4dihydro-2H-pyran in THF as solvent and room temperature conditions

Experimental

Entry 7 8

H5 CH3

Results and Discussion

Conclusion