Scheme 8. Two step synthesis of non-fluorinated VCP-47; activation energies to TS5 (ΔG ^‡ value (in blue) were calculated using (U)B3LYP/6-31G* from intermediate 47, gas phase, 298 K, Spartan'10, using conformationally simpler Me ester, units are kcal mol^–1). Conditions: (i) ZnEt₂ (1 M in hexane, 5 eq.), CH₂I₂ (10 eq.), 0 °C to r.t., 2.5 h; (ii) TEMPO (0.1 eq.), BAIB (1.1 eq.), DCM, r.t., 3.5 h; (iii) Ph₃P C(H)CO₂Et (1.3 eq.), 20 h.