CC BY 4.0 · SynOpen 2018; 02(04): 0276-0284
DOI: 10.1055/s-0037-1610665
paper
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Substituent-Dependent Chemoselective Synthesis of Highly Functionalized­ Benzo[h]quinolines and 4-Benzylpyrans from 2-Methyl-5-nitro-benzonitrile

Rahul Panwar
,
Shally,
Ranjay Shaw
,
Amr Elagamy
,
Chandan Shah
,
Ramendra Pratap*
Department of Chemistry, University of Delhi, North campus, Delhi, India-110007, India   Email: ramendrapratap@gmail.com   Email: rpratap@chemistry.du.ac.in
› Author Affiliations
RP thanks CSIR, New Delhi (No. 02(0286)/16/EMR-II) for research funding. RP and S thank the University Grants Commission (UGC, New Delhi) and RS thanks CSIR, New Delhi for Senior Research Fellowships. The authors thank the University of Delhi for providing research funding and USIC, Delhi University for providing the instrumentation facility
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Publication History

Received: 01 October 2018

Accepted after revision: 04 October 2018

Publication Date:
30 October 2018 (online)


Dedicated to Prof. Uli Kazmaier on his 59th birthday

Abstract

A facile, efficient and atom-economic synthesis of highly substituted benzo[h]qninolines was established by reaction of 2-methyl-5-nitrobenzonitrile with suitably functionalized 2H-pyran-2-ones under basic conditions. We observed that the presence of a thiomethyl group at the C-4 position of pyran provides 6-aryl-4-(2-cyano-4-nitrobenzyl)-2-oxo-2H-pyran-3-carbonitrile exclusively without any trace of benzo[h]quinolines. Depending on the nature of the functional group at C-4 of the pyran ring, different products were achieved. To probe the mechanism, we performed control experiments and isolated 3-(1-amino-7-nitro-3-thiophen-2-yl-naphthalen-2-yl)-3-piperidin-1-yl-acrylonitrile, which, on further treatment with base, provided the benzo[h]quinolines. The structure of one the products was characterized by single-crystal X-ray diffraction.

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