Synthesis of Nitrogen Heterocycles via Photochemical Ring Opening of Pyridazine N-Oxides.

A photochemical method for the direct synthesis of 1H-pyrazoles from pyridazine N-oxides was developed. This chemistry features a regioselective approach to nonsymmetrically substituted pyridazine N-oxides. Herein, we highlight the first strategic use of photoinduced ring-opening reactions of 1,2-diazine N-oxides for the preparative synthesis of nitrogen heterocycles.

Formation and in situ reactions of hypervalent iodonium alkynyl triflates to form cyanocarbenes.

The conversion of readily available silylalkynes, iodobenzene diacetate, and azide anions was utilized to form and react cyanocarbenes. A copper(II)-catalyzed reaction was found to react in a different manner. Both of these methods benefit from the formation and in situ reaction of hypervalent iodonium alkynyl triflates in O-H insertion reactions.