Triflic Acid Mediated Fries Rearrangement of 3-Dienyl-2-azetidinones: Facile Synthesis of 3-(But-2-enylidene)quinolin-4(3H)-ones

beta-Lactam-synthon-interceded synthesis of 3-(but-2-enylidene)quinolin-4(3H)-ones has been described via triflic acid mediated Fries rearrangement of 3-butadienyl-2-azetidinones. The described protocol provides a direct access to C-3 functionalized quinolin-4(3H)-ones and does not suffer from the disadvantages associated with conventional routes.