Dehydrogenative [2 + 2 + 1] Heteroannulation Using a Methyl Group as a One-Carbon Unit: Access to Pyrazolo[3,4-c]quinolines

 

Dehydrogenative [2 + 2 + 1] Heteroannulation Using a Methyl Group as a One-Carbon Unit: Access to Pyrazolo[3,4-c]quinolines

Guo-Bo Deng^†, Hai-Bing Li^†, Xu-Heng Yang^†, Ren-Jie Song^*†, Ming Hu^†, and Jin-Heng Li^*†‡

^† State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China

^‡ State Key Laboratory of Applied Organic Chemistry Lanzhou University, Lanzhou 730000, China

Org. Lett., Article ASAP

DOI: 10.1021/acs.orglett.6b00618

Publication Date (Web): April 28, 2016

Copyright © 2016 American Chemical Society

*E-mail: srj0731@hnu.edu.cn., *E-mail: jhli@hnu.edu.cn.

http://pubs.acs.org/doi/abs/10.1021/acs.orglett.6b00618

 A practical and straightforward access to pyrazolo[3,4-c]quinolines by molecular sieve mediated dehydrogenative [2 + 2 + 1] heteroannulation of N-(o-alkenylaryl)imines with aryldiazonium salts is described using a sp³-hybrid carbon atom as a one-carbon unit. The reaction enables the formation of three new chemical bonds, a C–C bond and two C–N bonds, in a single reaction and features simple operation and excellent functional group tolerance.

/////////Dehydrogenative [2 + 2 + 1] Heteroannulation,   Pyrazolo[3,4-c]quinolines

A continuous-flow process for the preparation of m-nitrothioanisole has been set up. The starting material m-nitroaniline was diazotized to give diazonium chloride, followed by azo-coupling with sodium thiomethoxide to give 1-(methylthio)-2-(3-nitrophenyl)diazene, then dediazoniated to gain m-nitrothioanisole in high yield. The continuous-flow process minimized accumulation of the energetic intermediate diazonium salt and has a better capacity for adapting large-scale production. A solvent was introduced in the azo-coupling section to create a biphasic flow system. Side products were inhibited eminently in this flow process.

Continuous-Flow Process for the Synthesis of m-Nitrothioanisole

Zhiqun Yu^†, Xiaoxuan Xie^†, Hei Dong^†, Jiming Liu^‡, and Weike Su^*†‡

^† National Engineering Research Center for Process Development of Active Pharmaceutical Ingredients, Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hangzhou 310014, P. R. China

^‡ Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, P. R. China

Org. Process Res. Dev., Article ASAP

DOI: 10.1021/acs.oprd.6b00023

Publication Date (Web): March 24, 2016

Copyright © 2016 American Chemical Society

*Tel.: (+86)57188320899. E-mail: pharmlab@zjut.edu.cn.

http://pubs.acs.org/doi/abs/10.1021/acs.oprd.6b00023
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