Synthesis of symmetrical pyridines by iron-catalyzed cyclization of ketoxime acetates and aldehydes
Synthesis of symmetrical pyridines by iron-catalyzed cyclization of ketoxime acetates and aldehydes
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Corresponding authors
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Key Laboratory of Synthetic and Nature Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science, Northwest University, Xi'an 710127, P.R. China
E-mail: guanzhh@nwu.edu.cn
E-mail: guanzhh@nwu.edu.cn
Green Chem., 2017, Advance Article
DOI: 10.1039/C6GC03137D
http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C6GC03137D?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract
A novel and facile iron-catalyzed cyclization of ketoxime acetates and aldehydes for the green synthesis of substituted pyridines has been developed. In the presence of a FeCl3 catalyst, this reaction exhibited a good functional group tolerance to produce 2,4,6-triarylsubstituted symmetrical pyridines in high yields in the absence of any additive. A gram-scale reaction sequence was performed to demonstrate the scaled-up applicability of this synthetic method.
4-Phenyl-2,6-di-p-tolylpyridine (3bb). Yield 70% (47.0 mg); Yellow solid; mp 148-150 o C; S-3
1 H NMR (400 MHz, CDCl3): δ 8.09 (d, J = 8.0 Hz, 4H), 7.82 (s, 2H), 7.72 (d, J = 7.2 Hz, 2H), 7.52-7.45 (m, 3H), 7.31 (d, J = 8.0 Hz, 4H), 2.42 (s, 6H).
13C NMR (100 MHz, CDCl3): δ 157.3, 149.9, 139.2, 138.9, 136.8, 129.4, 129.0, 128.8, 127.1, 126.9, 116.5, 21.3.
HRMS Calcd (ESI) m/z for C25H22N: [M+H] + 336.1747. Found: 336.1731.
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