... Chemistry The synthesis of azides A1–A4 (Fig. 1) is outlined in Scheme 1. The N-sulfonation of l-alaninol (1a) or l-phenylalaninol (1b) to yield 2a–d was followed by the generation of the O-methylsulfonyls (3a–d), and finally az- idation with NaN3 to obtain 4a–d (A1–A4) [13,14]. ...