Metal nitrate promoted highly regiospecific ortho–nitration of phenols: Application to the synthesis of nitroxynil

Abstract

Highly regiospecific ortho–nitration of electronically diverse phenols is accomplished using Fe(NO₃)₃.9H₂O for electron–rich and Cu(NO₃)₂.6H₂O for electron–deficient phenols as the cheap nitrating agents. The reaction is carried out in CH₃CN at 90 °C under mild and neutral conditions where structurally diverse phenols afford exclusively ortho–nitration products in moderate to good yields with outstanding tolerance of functional groups. The synthetic application of this strategy was established by achieving the bioactive compound nitroxynil.

Graphical Abstract

Keywords:

• Cheap nitrating agents
• metal nitrates
• ortho-nitration
• phenol carbonates

Additional information

Funding

Z. Iqbal and A. Joshi are grateful to UGC–New Delhi and NIT Uttarakhand respectively for their fellowships. The authors gratefully acknowledge the financial support from DST–SERB [103/2014 dt. 18.07.2015], NIT Uttarakhand and TEQIP–III.