SYNTHESIS OF URUSHI LIPID

对这两种工艺合成漆酚进行了研究。一种是以呋喃化合物为原料的工艺，另一种是以藜芦醇为原料的工艺。前者不需要保护邻苯二酚环上的活性羟基，但存在如何构筑邻苯二酚环的问题。研究该工艺的目的是寻找更好的漆醇前驱体。以呋喃类化合物为起始原料合成了漆酚前体。通过电氧化、加氢、克莱森缩合等步骤对5-取代四氢呋喃类化合物进行了处理。2，5-二甲氧基四氢-2-甲酰基乙酸甲酯(I)是由2-呋喃甲酸甲酯(I)在碱催化下与卤代烷反应得到的alpha-(2，5-dimethoxytetrahydro-2-froyl)-slpha-alkylacetate(II).甲酯(Ii)是漆酚的前体，通过水解转化为漆酚。很明显，溶剂和卤代烷的选择对(II)的产率有影响。在另一种使用藜芦醇的过程中，存在的问题是如何保护反应性羟基以及如何将其从保护中回收。第二，如何构建与天然脂类具有相同构型的侧烷基碳骨架。对这些问题的研究结果表明，用乙酰氧基取代藜芦醇的甲氧基，可以避免伴随羟基回收的副反应。侧链烷基或亚烷基的构型要求与天然乌鲁士脂类的构型在立体化学上一致。利用Wittig反应合成碳骨架是可行的，与天然脂类几乎一致。

Synthesis of urushiol was studied on the two process. One is the process which uses furan compound, and another process uses veratrole as starting material, respectively. The former process has no need for the protection of reactive hydroxyl groups of catechol ring, but it has a problem how to build catechol ring. The target of the study on this process is to find better precursor of urusiol. Fran compounds were used as starting materials forsynthsizing the precursor of urushiol. 5-substituted tetrahydrofuran compounds were treated through many steps such as electro-oxidation, hydrogenation and claisen condensation, etc, sequentry. Methyl 2,5-dimethoxyterahydro-2-froylacetate (I) is formed from methyl 2-furoate by these treatments, (I) reacted with alkyl halide in the presence of base catalysis and gave methyl alpha-(2,5-dimethoxytetrahydro-2-froyl)-slpha-alkylacetate(II). (II) is a precursor of urusiol and is converted to urushiol by hydrolysis. It became clear that the selection of solvent and alkyl halide had an influence on the yield of (II). Aprotic solvent and alkyl iodide gave good results.In another process using veratrole, the problems are, first, how to protect the reactive hydroxyl groups and how to retrieve them from protection. And second, how to build carbon skeleton of side alkyl group which has identical configuration with that of natural lipid. The results of the research on these problems indicates that the replacement of methoxy group of veratrole with acetoxy group enables ot aviod the side reactions accompanied with retrieval of hydroxylgroups. And the configuration of side alkyl or alkylene group is required to be coincident with that of natural urushi lipid stereochemically. It is practicable to synthesize carbon skeleton, by using wittig reaction, almost identical with natural lipid.