Polystyrene-supported benzenesulfonyl azide

Green, G. M., Peet, N. P., Metz, W. A. Polystyrene-Supported Benzenesulfonyl Azide A Diazo Transfer Reagent That Is Both Efficient and Safe. J. Org. Chem. 2001, 66, 2509-2511. 

Alternate Name polystyrene-supported benzenesulfonyl azide, PS-TsA. 

Preparative Methods the title reagent can be prepared in one step by the reaction of polystyrene-supported benzenesulfonyl chloride (100-200 mesh, available from Aldrich, 51,623-6 [163894-16-4], as 1% DVB cross-linked polystyrene resin with a loading of 1.5-2.0 mmol/g) with sodium azide (1.5 equiv) in DMF/H2O (reaction complete at rt in 16 h). 

Recently, two methods were published that have attracted some interest, because no metal salts are necessary as oxidation reagents. Shi and Xu (1990) found that substituted (trifluoromethyl)-diazoalkanes (CF3CRN2, R = alkyl or aryl) are obtained by refluxing trifluoromethyl ketones and 2,4,6-tri(isopropyl)benzenesulfonyl hydrazone in a methanolic solution of KOH. Kumar (1991) synthesized a-diazocar-bonyl compounds under tri-phase phase-transfer catalysis using a polystyrene-supported (tributyl)(methyl)-ammonium chloride catalyst, methanesulfonyl chloride, NaN3, and methylsulfonyl azide in 1,2-dichloroethane and a carbonyl-activated substrate (69-94% yield). 

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