1. Synthesis of O-alkylazidoximes and their reactions in electrophilic media
Debra D. Dolliver, Southeastern Louisiana University, Hammond, Louisiana
Organoazides are becoming more widely used in synthetic schemes , and there are ample reports of compounds where the azide functionality if attached to an sp2-hybridized carbon. Therefore, it is surprising that there is only one reference to an O-alkylazidoxime in the literature. We have now completed development of a general route to the synthesis of O-alkylazidoximes and we have investigated their stability, their reactivity under 1,3-dipolar cycloaddition conditions, and the effect of solvent and electrophilic species on two competing pathways for reaction in electrophilic media.
These O-alkylazidoximes (2Za-f) were successfully synthesized in moderate to excellent yields with both electron-donating and electron-withdrawing substituents on the aromatic ring by reacting O-alkylbenzohydroximoyl bromide with sodium azide in dimethylsulfoxide (Scheme 1)
We have completed studies on reactions of 2Za with electrophiles (trifluoroacetic acid and acetyl chloride) in a variety of solvents to assess the effect of solvent polarity on product distribution (urea [3] vs. tetrazole [4]). We have found that in all solvents, treatment with trifluoroacetic acid favors urea formation. Also, in all solvents, treatment with acetyl chloride favors tetrazole formation exclusively. Computational studies have indicated that urea should be the thermodynamically favored product. We are now assessing the effect of equilibrium concentrations of the intermediate formed by interaction of 2Za with the electrophile. This work has been performed solely by undergraduate students and a manuscript is currently being perpared for publication.
Scheme 2
Scheme 1