Sulfamic Acid as an Effective Catalyst in Solvent‐Free Synthesis of β‐Enaminoketone Derivatives and X‐ray Crystallography of Their Representatives

Abstract

Two types of β‐enaminoketone derivatives of 3‐(2‐oxo‐2‐arylethylidene)‐3,4‐dihydro‐1H‐quinoxalin‐2‐ones and 3‐(2‐oxo‐2‐arylethylidene)‐3,4‐dihydro‐benzo[1,4]oxazin‐2‐ ones were effectively and conveniently prepared in good to excellent yields under solvent‐free conditions via the catalysis of sulfamic acid in the corresponding condensations of o‐phenylenediamine and o‐aminophenol with ethyl 2,4‐dioxo‐4‐arylbutyrate respectively. The compounds were confirmed by IR, ¹H NMR, and ¹³C NMR, and a representative was further determined by X‐ray crystallography.

Keywords:

• Catalysis
• β‐enaminoketone
• solvent free
• sulfamic acid
• X‐ray crystallography

Acknowledgment

We are grateful for the financial support from the Nature Science Foundation of Zhejiang Province (Project No. R405465).