(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).Purification: filter and wash with H2O, DMF, and finally with ...