One-Pot O2‑Oxidation and the Horner–Wadsworth–Emmons Reaction of Primary Alcohols for the Synthesis of (Z)‑α,β-Unsaturated Esters

We developed one-pot oxidation/olefination procedures of primary alcohols giving Z-α,β-unsaturated esters 3. TEMPO-(CuCl or CuBr2)-(2,2′-bipyridine) (1:1:1) catalyzed O2 oxidation of primary alcohols in the presence of Z-selective Horner–Wadsworth–Emmons reagent 1b and K3PO4 or NaH gave 3 with Z/E = 84:16 to 96:4 in high yields. A stepwise reaction was also developed. After TEMPO-CuBr2-(2,2′-bipyridine)-K3PO4 (1:1:1:1) catalyzed O2 oxidation of alcohols in MeCN, the resulting mixture was treated with a THF solution of 1b and t-BuOK at −78 °C to 0 °C, giving 3 with higher selectivity (Z/E = 91:9 to 99:1).