Base‐Promoted Michael Addition/Smiles Rearrangement/ N‐Arylation Cascade: One‐Step Synthesis of 1,2,3‐Trisubstituted 4‐Quinolones from Ynones and Sulfonamides.

A general, practical, and environmentally friendly protocol to synthesize 1,2,3‐trisubstituted 4‐quinolones from readily available ynones and sulfonamides was developed. The construction of one C−C bond and two C−N bonds via cleavage of one N−S, one C−S, and one C−X (X=F, Cl, Br, O) bond is achieved under transition‐metal‐free conditions in one step. This transformation generates 1 equiv. of sulfur dioxide and 1 equiv. of hydrogen halide as the byproducts. The broad substrate scope and functional group tolerance are demonstrated by 52 examples of 1,2,3‐trisubstituted 4‐quinolones. A preliminary mechanistic study supports a sequential Michael addition/Smiles rearrangement/N‐arylation reaction pathway. [ABSTRACT FROM AUTHOR]