1: Et3N / acetone / 2 h / Ambient temperature 2: 1.) Et3N, diphenylphosphoryl azide (DPPA) / 1.) MeCN, reflux, 1 h, 2.) MeCN, reflux, 1 h View Scheme

diphenylphosphoranyl azide; triethylamine 1.) MeCN, reflux, 1 h, 2.) MeCN, reflux, 1 h; Yield given. Multistep reaction;