For the first time, the [4 + 3] or [2 + 1] annulation of crotonate-derived sulfur ylides with arylidenemalononitrile or arylidene-1H-indene-1,3(2H)-dione is reported using Na2CO3 as the base.

An unparalleled [4 + 2]-annulation of prop-2-ynylsulfonium salts with isatoic anhydrides was developed, affording a series of 4-quinolones with a alkylthio group in medium to good yields under mild conditions. In this reaction type, the prop-2ynylsulfonium salt serves as a C2 synthon and sulfide does not act as a leaving group, providing facile access to organosulfur compounds. The resulting quinolone products could be further transformed to a diverse range of synthetically useful compounds.