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.

Lophine (2,4,5-triphenylimidazole) and sixteen of its derivatives bearing substituents in the 2-phenyl group have been synthesized and characterized. The fluorescence excitation and emission spectra in neutral and basic solution in 70 % dimethylsulfoxide-30 % water have been determined. The chemiluminescent intensities in 70% DMSO-30% water, 0.33 N in NaOH have been measured. The maximum chemiluminescent emission wavelength was found to fall at 530 m p for all compounds except the nitro derivatives whose intensities were too low to measure. The compounds bearing substituents in the meta and/or para positions of the 2-phenyl group give linear Hammett plots. The value of p is -1.96kO.06. The constant emission wavelength and linear Hammett relation is interpreted in terms of the same mechanism and emitting species for all the compounds studied.

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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.