Transition-Metal-Free Cascade Approach toward 2-Alkoxy/2-Sulfenylpyridines and Dihydrofuro[2,3-b]pyridines by Trapping In Situ Generated 1,4-Oxazepine

Guolin Cheng*, Lulu Xue, Yunxiang Weng and Xiuling Cui*

*College of Materials Science & Engineering & Institutes of Molecular Medicine and School of Biomedical Sciences, Huaqiao University, Xiamen 361021, China, Email: glchenghqu.edu.cn, cuixl@hqu.edu.cn

G. Cheng, L. Xue, Y. Weng, X. Cui, J. Org. Chem., 2017, 82, 9515-9524.

DOI: 10.1021/acs.joc.7b01541

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Abstract

Trapping of in situ generated active intermediate 1,4-oxazepines, formed from base-promoted 7-exo-dig cyclization reaction of N-propargyl enaminones, with alcohols/thiols and aldehydes provides 2-alkoxy/2-sulfenylpyridines and dihydrofuro[2,3-b]pyridines in good yields within 30 min at room temperature. This cascade reaction generates 1 equiv of H₂O as the sole byproduct.

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proposed mechanism

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Key Words

pyridines, 2-pyridones

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ID: J42-Y2017