2-溴-3-甲基-1,4-二甲氧基萘的合成

以2-甲基萘醌为原料,经过催化氢化、甲醚化和溴化3步反应,合成了维生素K2的重要中间体2-溴-3-甲基-1,4-二甲氧基萘(1)。以钯碳为催化剂加氢还原,得到了2-甲基-1,4-二羟基萘(3),收率98.8%;3在碱性条件下用硫酸二甲酯进行甲氧基保护,生成2-甲基-1,4-二甲氧基萘(4),收率95.1%;4与溴反应可以得到1,收率90.1%。3步反应总收率由传统方法的48.7%提高到84.6%。

Synthesis of 2-bromo-3-methyl-1, 4-dimethoxynaphthalene

2-Bromo-3-methyl-1,4-dimethoxynaphthalene,an im-portant intermediate of menaquinone,was synthesized through three-step process employing 2-methyl-1,4-naphtho-quinone as the starting material.The first catalytical hydrogenation with pal-ladium/activated carbon as the catalyst gave a 98.8% yield.Forthe second step,2-methyl-1,4-naphthohydroquinone reacted with dimethyl sulfate in aqueous alkali,95.1% yield was realized.The target product was obtained through the reaction between 2-methyl-1,4-dimethoxynaphthalene and bromine with 90.1% yield.The overall yield reached 84.6%.