1: methanol; (4S,2Z)-4-methyl-5-trityloxypent-2-ene With toluene-4-sulfonic acid T=20°C; 4 h; 2: With oxalyl dichloride; dimethyl sulfoxide in dichloromethane T=-78°C; Swern oxidation; 0.583333 h; 3: triphenyl(1-[ethoxycarbonyl]ethylidene)phosphorane Further stages;

1: methanol; (4S,2Z)-4-methyl-5-trityloxypent-2-ene With toluene-4-sulfonic acid T=20°C; 4 h; 2: (2S,3Z)-2-methylpent-3-ene-1-ol With oxalyl dichloride; dimethyl sulfoxide in dichloromethane T=-78°C; Swern oxidation; 0.583333 h; 3: With triethylamine in dichloromethane T=-78 - 0°C; 1.16667 h;

toluene-4-sulfonic acid in dichloromethane; water T=20°C; 4 h; Inert atmosphere;

1: methanol; (4S,2Z)-4-methyl-5-trityloxypent-2-ene With toluene-4-sulfonic acid in dichloromethane; water T=20°C; 4 h; Inert atmosphere; 2: With sodium hydrogencarbonate; Dess-Martin periodane in dichloromethane T=0°C; Dess-Martin oxidation; 3 h; Inert atmosphere; 3: methyl 2-(triphenylphosphoranylidene)propionate in dichloromethane T=0°C; 0.0833333 h; Inert atmosphere; optical yield given as percent ee;

1: methanol; (4S,2Z)-4-methyl-5-trityloxypent-2-ene With toluene-4-sulfonic acid in dichloromethane; water T=20°C; 4 h; Inert atmosphere; 2: With oxalyl dichloride; triethylamine in dichloromethane; dimethyl sulfoxide T=-78 - 0°C; Swern oxidation; 1.75 h; Inert atmosphere; 3: triphenyl(1-[ethoxycarbonyl]ethylidene)phosphorane in dichloromethane; dimethyl sulfoxide T=-78 - 20°C; Inert atmosphere; optical yield given as percent ee;