Scheme 1.

Synthesis of macrocidin Z (6). Reagents and conditions: (a) DCC, DMAP, (R)-benzyl-2-oxazolidinone, CH₂Cl₂, 23 h; (b) 1. NaHMDS, THF, −78 °C, 30 min, 2. MeI, 4.5 h; (c) LiOH, H₂O₂, THF/H₂O (2:1); (d) Meldrum´s acid, DMAP, EDC∙HCl, CH₂Cl₂, rt, 2 h; (e) 10, DMAP, EDC∙HCl, CH₂Cl₂, 0 °C, rt, 2 h; (f) NEt₃, DMAP, CH₂Cl₂, rt, 24 h; (g) Grubbs II catalyst, CH₂Cl₂, ∆, 15 h; (h) TFA, CH₂Cl₂, rt, 15 min. DCC = dicyclohexylcarbodiimide; DMAP = dimethylaminopyridine; NaHMDS = sodium hexamethyldisilazanide; THF = tetrahydrofuran; EDC = 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide; TFA = trifluoroacetic acid.