3,5-Dimethoxybenzoic acid reacts with lithium hydride to form salt which is acylated by n-butyllithium to synthesize 1-(3,5-dimethoxyphenyl)-1-pentanone,and then this ketone is reduced by Wolff L-Huangminglong reaction under 210 ℃ to form 3,5-dimethoxy-1-phenylbenzene that refluxs with pyridine and concentrated hydrochloric acid for 2 h at 200 ℃ to prepare 5-pentyl resorcinol.
以3,5-二甲氧基苯甲酸为起始原料,与LiH在室温下反应5h生成苯甲酸盐,生成的盐再与正丁基锂进行酰化反应得到3,5-二甲氧基苯戊酮,进而在210℃以下进行乌尔夫-黄鸣龙反应将酮还原,生成3,5-二甲氧基戊苯,所得产物与吡啶盐酸盐熔融,于200℃回流2h,脱甲基制得5-戊基间苯二酚,总收率达60。