Herein, a very stable and highly reactive insoluble polymer-supported organotin azide was prepared from a Merrifield resin and its azide loading was determined by elemental analysis. This immobilized azide was employed in one-pot diazotization-azidodediazoniation of aromatic amines to provide a wide range of aryl azides in very good yields under mild conditions. On the other hand, this supported reagent was successfully applied in the 1,3-dipolar cycloaddition reaction with aromatic nitriles to provide 5-aryl 1H-tetrazoles in good yields. In addition, the recyclability of tin azide from the supported dibutyltin sulfonate recovered in the synthesis processes was reported. The developed methods allow the recycling and reuse of the supported tin azide, without significant loss of reactivity after four cycles in our reaction scale and less than 20 ppm of residual tin concentration in final products without additional purification.
An efficient and straightforward method for one-pot synthesis of aryl azides from the corresponding amines, employing tributylstannyl azide as transfer reagent of N 3 group is described. In this procedure diazotization of aryl amines occurs under mild conditions using tert-butyl nitrite (t-BuONO) and p-toluenesulfonic acid (TsOH). A variety of substituted aryl amines, with both electron-withdrawing and electron-donating groups were transformed into aryl azides in good to excellent yields. An important advantage of the present method is that, despite their high toxicity, tin byproducts can be reconverted into the starting tributylstannyl azide by treatment with sodium azide (NaN 3 ) and reused after chromatographic separation of the aryl azide.
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