[6655-31-8] · C6H4N4O4S · o-Nitrobenzenesulfonyl Azide · (MW 228.21)
(1,3-dipolar reagent that undergoes cycloaddition to alkenes, enamines, enol ethers, and enynes1)
Physical Data: mp 71-73 °C.
Solubility: sol most organic solvents.
Preparative Method: by the reaction of o-nitrobenzenesulfonyl chloride with an aqueous acetone solution of Sodium Azide, first at 0 °C and then at 25 °C.2
Purification: crystallization from ethanol.2
Handling, Storage, and Precautions: azides should be expected to be sensitive to electrical, thermal, and/or mechanical shock. The parent sulfonyl azide, benzenesulfonyl azide, in the crude state, detonates violently when heated.
o-Nitrobenzenesulfonyl azide has been used for the ring enlargement-conversion of methylenecycloalkanes into the homologous o-nitrobenzenesulfonimidocycloalkanes. For example, methylenecycloheptane affords the imido product in quantitative yield. Hydrolysis of the imide with acid then affords the corresponding ketone (eq 1).3
The reagent has also been employed for the cycloaddition-rearrangement of both methyl and trimethylsilyl enol ethers (eqs 2 and 3).4,5
Decomposition of the reagent in boiling benzene-cyclohexene affords a quantitative yield of a 3:1 mixture of imide and enesulfonamide (eq 4).6
With a cyclic enamine, o-nitrobenzenesulfonyl azide affords an N-sulfonyl amidine following decomposition of an unstable intermediate triazoline (eq 5).7
The reaction of o-nitrobenzenesulfonyl azide with an ynamine leads to a 2-diazoalkanamidine as the only isolable product. An equilibrium between the amidine and the ring-closed triazole exists, however, in solution (eq 6).8
Emory University, Atlanta, GA, USA