N,N,N-trimethyl-1-phenylmethanaminium tribromide; calcium carbonate in methanol; dichloromethane

1: 3,5-dibromo-4-(di-tert-butyl((2E,6E,10E,14E,18E)-2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22-hexaenyloxy)silyloxy)benzoic acid With 1,1'-carbonyldiimidazole in dichloromethane T=23°C; 0.5 h; 2: With dihydrogen peroxide in dichloromethane T=-78 - -20°C; 3: diazomethane With tetrabutylammonium (meta)periodate; pyridine hydrogenfluoride; periodic acid in tetrahydrofuran; dichloromethane; water Further stages;

1: 3,5-dibromo-4-(di-tert-butyl(nonaprenyloxy)silyloxy)benzoic acid With 1,1'-carbonyldiimidazole in dichloromethane T=23°C; 0.5 h; 2: With dihydrogen peroxide in dichloromethane T=-78 - -20°C; 3: diazomethane With tetrabutylammonium (meta)periodate; pyridine hydrogenfluoride; periodic acid in tetrahydrofuran; diethyl ether; dichloromethane; water Further stages;

acetyl chloride 18 h; Ambient temperature;

N-bromosuccinmide in acetonitrile 4 h; Ambient temperature;

sodium hydroxide

2: (i) HCl, CH2Cl2, (ii) Et3N View Scheme