Pyrazole is an essential structural component of many pharmaceuticals and agrochemicals. The synthesis of pyrazoles has been a subject of intense research for several decades. Many transformations are now available...

Divergence in the PBu3-catalyzed [3+2] annulation of phenacylmalononitriles with allenoates, controlled by the γ-substitution on allenoates, offers a tunable synthesis of multifunctionalized cyclopentene carboxamides and cyclopentenols. An unprecedented formation of...

Reported in this Letter is a silver-catalyzed reaction between o-alkynylaryl aldehydes and trifluorodiazoethane that enables an expedient synthesis of trifluoromethylated benzo [d]oxepines. The reaction works through a silver-promoted 6-endo-dig cyclization of o-alkynylbenzaldehydes for the generation of an isochromenylium intermediate, which upon a ring-expansive addition of trifluorodiazoethane delivers a novel class of trifluoromethylated benzoxepine frameworks. This strategy was applied to the synthesis of phosphonylated benzo[d]oxepines using the Seyferth−Gilbert reagent.

An interesting substrate-controlled reactivity switch has been observed in the reaction of α-fluoro-β-ketoamides with arynes. The reaction of secondary α-fluoro-β-ketoamides with aryne provided access to α-aryl-α-fluoroacetamides through an arylation/deacylation sequence....