Synthesis of a Class of Fused δ‐Sultone Heterocycles via DBU‐Catalyzed Direct Annulative SuFEx Click of Ethenesulfonyl Fluorides and Pyrazolones or 1,3‐Dicarbonyl Compounds

Abstract

Abstract(E)‐2‐(hetero)arylethenesulfonyl fluorides and (E,E)‐1,3‐dienylsulfonyl fluorides are bis‐electrophiles and rare members of the sulfonyl fluoride family with limited information being known of their reactivity and synthetic utility. The direct annulation reaction of these 2‐substituted ethenesulfonyl fluorides with medicinally important enolizable pyrazolones and 1,3‐dicarbonyl compounds utilizing catalytic DBU in DCM under mild conditions leads to over 50 structurally diverse δ‐sultone fused heterocycles with a pyrazolone ring or a cyclic enone, respectively, in good to excellent yield. The double bond at the 1‐position adjacent to the sulfonyl fluoride group in 1,3‐dienylsulfonyl fluoride is the chemoselective site of reactivity but is less reactive than the double bond of arylethenesulfonyl fluoride. High turnover and robustness of construction for these fused heterocycles, including the novel fused pyrazolone δ‐sultone heterocycle series, may make compounds like these attractive to drug discovery, development and material science.magnified image