Transition-metal-free synthesis and photophysical studies of highly functionalized (E)-stilbenes

Metal-free synthesis of highly functionalized (E)-stilbenes cored with electronic donor and acceptor functionalities was achieved through a carbanion-induced ring transformation reaction between (E)-4-(4-(dimethylamino)phenyl)but-3-en-2-one 12 and 6-aryl-2H-pyran-2-ones 9 in the presence of a base. The procedure has several advantages, including mild reaction conditions, readily available precursors, metal-free synthesis, simple setup, and the synthesis of various substituted regioselective (E)-stilbenes in good yields. All the synthesized compounds 13a–j were found to be thermally stable and exhibited fluorescence in the range of 436–490 nm. A considerable positive solvatochromic behaviour in different solvents of varying polarity was observed, and the concentration study indicated the non-aggregating behaviour of all the synthesized compounds.