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

We developed one-pot oxidation/olefination procedures of primary alcohols giving Z-α,ß-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).