1: 97 percent / toluene-p-sulphonic acid/silica gel / H2O; tetrahydrothiophene 1,1-dioxide; CH2Cl2 2: 850 mg / diethyl ether / 60 h 3: 64 percent / lithium triethylborohydride / tetrahydrofuran / 0.25 h / 20 °C 4: 61 percent / H2 / platinum oxide / 18 h / 150 °C / ethyl palmitate View Scheme

dimsyl sodium; trimethyl orthoformate 1.) 60 h, reflux, butyronitrile; 2.) 16 h, n-hexane; Yield given. Multistep reaction;