Synthesis of 8-Aryl-6-Thioxo-6H-1,9-Dioxa-7-Aza-Cyclopenta[a]Naphthalen-3-One under Solvent-Free Conditions at Ambient Temperature

Abstract

We report a green and efficient method for the synthesis of 8-aryl-6-thioxo-6H-1,9-dioxa-7-aza-cyclopenta[a]naphthalen-3-one from the condensation of ammonium thiocyanate and acid chlorides with 7-hydroxy-3-coumaranone in the presence of catalytic amounts of N-methylimidazole under solvent-free conditions at ambient temperature. This new protocol offers advantages, such as mild reaction conditions, short reaction time, easy work-up, and use of an inexpensive and nontoxic catalyst, high yields of biological active products and does not involve any hazardous solvent. This prompted us to establish a novel oxazine ring formation method to find promising bioactive oxazine compounds. They are found to have exhibit diverse pharmacological properties.

Graphical Abstract

Keywords:

• 8-Aryl-6-thioxo-6H-19-dioxa-7-aza-cyclopenta[a]naphthalen-3-one
• 7-hydroxy-3-coumaranone
• acid chlorides
• ammonium thiocyanate
• N-methylimidazole
• solvent-free conditions

Disclosure statement

There are no conflicts of interest.