Synthesis of Quinolines by N-Deformylation and Aromatization via Solvent-Free, High-Speed Ball Milling

Abstract

The emerging technique of high-speed ball milling was first applied in the N-deformylation and aromatization reaction to synthesize quinolines. PEGs (polyglycols) were used to promote this solvent-free, solid-solid state reaction and good to excellent yields of the quinolines were obtained in short reaction times.

GRAPHICAL ABSTRACT

Keywords:

• Ball milling
• N-deformylation
• polyglycols
• quinolines
• solid-state synthesis

ACKNOWLEDGMENTS

We are grateful to the National Natural Science Foundation of China (No. 20876147) and Natural Science Foundation of Zhejiang Province (No. Y4090346) for financial support.

Notes

^a Reactions were run with 5 mmol of 1a, 10 mol% of PEGs, and 5.0 g NaCl.

^b Isolated yields.

^c 32 wt% KF.

^a Reactions were carried out with N-formyl-1,2-dihydroquinolines 1 (5 mmol), NaOH (0.3 g, 7.5 mmol), PEG 2000 (1 g, 0.5 mmol), and NaCl (5.0 g).

^b Isolated yields based on 1.

^c NaOH (0.4 g, 10 mmol) was used.

^a 5 mmol of 1a, 10 mol% of PEG, and 5.0 g NaCl were used.

^b The recovered reagent (including NaOH) was used with the addition of fresh 1.0 equiv. NaOH.

^c Isolated yields.