Iodine mediated one-pot synthesis of 3-cyano and 3-cyano-4-methylcoumarins

Abstract

2-Hydroxybenzaldehydes 1a-e on reaction with malononitrile 2 in the presence of iodine as catalyst give 3-cyanocoumarins 3a-e in one step under thermal heating as well as microwave irradiations. The latter conditions are much more efficient in terms of time (2-5 minutes) and yield as compared to thermal conditions (2-2.5 hours). Following similar procedure, 3-cyano-4-methylcoumarins 3f-i have also been prepared by the reaction of 2-hydroxyacetophenones 1f-i with malononitrile 2.

Keywords

• 3-cyanocoumarin/3-cyano-4-methylcoumarin
• malononitrile
• iodine
• microwave irradiation
• one-pot reaction