An environmentally benign cascade reaction of 1,2,3-indantriones with ethyl 2-(pyridine-2-yl)acetates for site-selective synthesis of 5H-isochromeno[4,3-b]indolizin-5-ones

Abstract

A novel approach was developed for the synthesis of 5H-isochromeno [4,3-b]indolizin-5-ones (ICIDOs) 3 through a cascade reaction of 1,2,3-indantriones 1 with ethyl 2-(pyridine-2-yl)acetates 2. Various 5H-isochromeno [4,3-b]indolizin-5-ones were produced by heating of the mixture of 1,2,3-indantriones and ethyl 2-(pyridine-2-yl)acetates for approximately 8 ​h in an environmentally-friendly PEG200 solvent with catalyst of a few drops of acetic acid. This approach has several advantages such as the use of an environmentally-friendly solvent, simple and practical operation (with filtration and washing and no column chromatography separation), good yields (up to 91%), use of commercially available raw materials, diverse target compounds, and products with potential biological activity.

Keywords

• Indolizines
• Site-selective
• Cascade reaction
• Environment benign
• Ethyl 2-(pyridine-2-yl)acetates