“…Succinimidyl diazoacetate (1) was synthesized with slight modification as described previously. [17,36] Catalysts 5, [37] 6, [27] 7a-c, [23] 8, [24] and 9 [25] were prepared as described in the literature. The activity of catalyst 8 decreases on storing; therefore, it was re-activated prior to use by dissolution in dry acetonitrile, warming at 60 8C for 10 min and evaporation of the solvent in a flow of argon.…”