The invention relates to a preparation method of a key intermediate 4-[(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-
naphthalene)methoxyl]
methyl benzoate (5) of new anti-
cancer medicine bexarotene. The method comprises the steps that an intermediate 1,1,4,4,6-pentamethyl-1,2,3,4-tetrahydronaphthalene (4) and commercially available chemical materials of mono-methyl terephthlate, chlorinating agents of
thionyl chloride or
oxalyl chloride or the like and solvents of aluminum
chloride,
dichloromethane and the like are directly subjected to a one-step reaction, and the intermediate (5) is obtained. Please see the formula in the description. According to the preparation method of the key intermediate 4-[(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-
naphthalene)methoxyl]
methyl benzoate (5) of the new anti-
cancer medicine bexarotene, the
reaction step is simplified, the raw materials are easy to obtain, the reaction condition is mild, the reaction yield is up to 95% (The literature method yield is 70%.), the product purity is larger than or equal to 98%, the step of preparing methoxycarbonyl
benzoyl chloride through virulent
phosphorus pentachloride in a literature method is omitted, a virulent and explosive chemical
reagent nitromethane used for a stable reactant is removed, the production cost is reduced, the production process is simplified, and the preparation method is very suitable for industrialized
mass production.