Process Improvement Strategy in the Synthesis of Dihydro [2, 3-B] Thieno Quinoline

An expeditious, simple, facile method and an environmentally benign method for the synthesis of dihydrothienoquinoline are herein described. The reaction of vinyl thione with PPA gave dihydrothienoquinoline in 38-60% yield under different classic conditions. Process improvement strategies employed for the synthesis of 2, 3–dihydro-4-methyl-thieno (2, 3-b) quinoline carried out with various cyclizing agents like dil.sulphuric acid, mixture of dil.sulphuric acid and dioxan, dil.sulphuric acid and methylene chloride etc. increased the yield substantially. Stirring with perchloric acid and acetonitrile at R.T gave appreciable yields (89%) of the dihydro compound. Microwave reactions of the compounds increased the percentage yield of products compared to conventional synthesis. There is also drastic reduction in the time of synthesis as anticipated

Author(s): Lalitha P  And Sivakamasundari

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