Tosyl azide ring closures with

Thus, 5-methoxypyrimidine 103 when treated with lithium tetramethylpiperidide (LTMP) and subsequently by tosyl azide led to formation of the 2-azido derivative 104, which spontaneously undergoes ring closure to 8-methoxytetrazolo[l,5-c]pyrimidine 105. 

The ability of non-racemic C2-symmetric aziridines 848 and 849 to undergo rapid nucleophilic ring-opening to provide synthetic equivalents for the j5-cation of aspartic acid illustrates the utility of the azide 822. Treatment of 822 with triphenylphosphine in refluxing benzene results in reduction of the azide to an amine that readily undergoes ring closure to aziridine 845. Subsequent tosylation of the secondary nitrogen affords 848 in 73% yield for the two steps. 

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