A new method for the synthesis of substituted indeno[1,2-b]thiophene with subsequent ring expansion to form substituted thieno[3,2-c]quinoline

摘要

2-Phenacylindan-1,3-dione (3) was treated with Lawesson's reagent (2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide) to form 2-phenyl-4H-indeno [1,2-b]thiophene-4-one (4). Compound 4 was subsequently reacted with hydroxyl amine to form the oxime (5), which, upon treatment with polyphosphoric acid, underwent ring expansion (Beckmann rearrangement) to give 2-phenylthieno[3,2-c]quinoline-4(5H)one.