para-Selective C−H functionalization of pyridines holds a significant value but remains underdeveloped. Site-switchable C−H functionalization of pyridines under easily tunable conditions expedites drug development. We recently reported a redox-neutral dearomatization−rearomatization strategy for meta-C−H functionalization of pyridines via oxazino pyridine intermediates. Here, we demonstrate that these oxazino pyridine intermediates undergo highly para-selective functionalization simply by switching to acidic conditions. A broad scope of para-alkylated and arylated pyridines is prepared through radical as well as ionic pathways. These mild and catalyst-free methods are applied to the late-stage para-functionalization of drugs using pyridines as the limiting reagents. Consecutive meta,para-difunctionalization of pyridines is also achieved with complete regiocontrol relying on the pH-dependent reactivity of oxazino pyridines.

A transition‐metal‐free aminocyanation of aryl alkynes has been achieved using indium tribromide, InBr3 or B(C6F5)3 as a Lewis acid. This aminocyanation protocol features with non‐toxic cyanide source, a good substrate scope and potentially valuable aminocyanation products. Mechanistic studies reveal the complex formation between Lewis acid and alkyne to produce in situ alkyne nitrile as a key intermediate. Further hydroamination of alkyne nitrile with arylamines affords the E‐selective (E:Z=70:30 to 90:10) β‐aminoacrylonitrile derivatives.