【摘要】 本文提出一合成5-羟基嘧啶的一般方法,即使用α-甲氧基-β-二羰基化合物、羰基酯或有关的化合物来与脒的衍生物缩合,得到的5-苯甲氧基嘧啶在氢解后生成相应的5-羟基嘧啶。并报告以苯甲氧基丙二酸二乙酯（ⅩⅣ）合成几种2-取代-4,5,6-三羟基嘧啶所得的结果。1.对于制备苯甲氧基乙酸乙酯（Ⅻ）的方法作了仔细的探索,提出了以苯甲氧基乙腈（Ⅺ）醇解为苯甲氧基乙酸乙酯的有效方法。2.以苯甲氧基乙酸乙酯与草酸二乙酯进行 Claisen 结合,再行裂解得到苯甲氧基丙二酸二乙酯（ⅩⅣ）。3.将ⅩⅣ与脒衍生物缩合得到以下2-取代-4,6-二羟基-5-苯甲氧基嘧啶:（ⅩⅤ,R=OH）,（ⅩⅥ,R=NH₂）,（ⅩⅦ,R=CH₃）,（ⅩⅧ,R=SH）和（ⅩⅨ,R=SC₂H₅）。以ⅩⅧ进行去硫反应（Raney 镍）得到（ⅩⅩ,R=H）;出乎意外的是在去硫反应过程中,苯甲基未受影响。这些5-苯甲氧基嘧啶都是稳定的化合物,祇有5-苯甲氧基巴比酸（ⅩⅤ）在空气中自行氧化;氧化产物证明是5-苯甲氧基-5-羟基巴比酸（ⅩⅩⅥ）。4.催化氢解苯甲氧基得到相应的2-取代-4,5,6-三羟基嘧啶:（Ⅲ,R=OH）,（ⅩⅪ,R=NH₂）,（ⅩⅫ,R=CH₃）和（ⅩⅩⅢ,R=H）。5.这些嘧啶与三氯化铁氨溶液,氢氧化钡和磷钼酸所发生的颜色反应显示了5-位羟基的芳香性,同时由于它们所共有的烯二醇结构,它们都有使2,6-dichlorophenolindo-phenol 脱色的作用。更多还原

【Abstract】 The chemistry of 5-hydroxylated pyrimidines and their preparative methods were briefly re-viewed.A route leading to the synthesis of 5-hydroxypyrimidines was suggested which involvesusing α-benzyloxy-β-dicarbonyl compounds,keto-esters or related substances as three-carbon com-ponents to condense with amidine derivatives and was exemplified in a preparation of various2-substituted 4,5,6-trihydroxypyrimidines from ethyl benzyloxymalonate.1.Methods of preparing ethyl benzyloxyacetate(Ⅻ)were examined critically and ex-plored.It was found that alcoholysis of benzyloxyacetonitrile(Ⅺ)constitutes a satisfactory routeto this compound.2.Ethyl benzyloxymalonate(ⅩⅣ)was prepared by Claisen condensation between ethylbenzyloxyacetate and ethyl oxalate followed by pyrolysis. 3.ⅩⅣ was caused to condense with various amidine derivatives to yield the following5-benzyloxypyrimidines:5-O-benzyl-dialuric acid(ⅩⅤ),2-amino-(ⅩⅣ),2-methyl-(ⅩⅦ),2-thiol-(ⅩⅧ)and 2-ethylthio-4,6-dihydroxy-5-benzyloxypyrimidine(ⅩⅨ).Desulphurization of(ⅩⅧ)with Raney nickel gave the 2-unsubstituted 4,6-dihydroxy-5-benzyloxypyrimidine(ⅩⅩ):the benzyl residue was found not removed in the desulphurization process.They are stable com-pounds except 5-O-benzyl-dialuric acid(ⅩⅤ)which undergoes oxidation in air.The oxidationproduct was identified to be 5-benzyloxy-5-hydroxybarbituric acid(ⅩⅩⅥ).4.The O-benzyl group could be split off by hydrogenolysis in the presence of Adams’palladous oxide catalyst to give respectively the following 5-hydroxypyrimidines:dialuric acid(Ⅲ),2-amino-(ⅩⅪ),2-methyl-(ⅩⅫ)and 2-unsubstituted 4,5,6-trihydroxypyrimidine(ⅩⅩⅢ).5.The aromatic character of 5-hydroxy group in these pyrimidines is reflected by theircolor reactions with ammoniacal ferric chloride,barium hydroxide and phosphomolybdic acidsolutions.In virtue of their common enediol structure,they decolorize 2,6-dichlorophenolindo-phenol solution.更多还原