3-Acetoxy-1,4-dibenzyl-3-[1-(2-methoxyethyl)ethenyl]piperazine-2,5-dione (32) and its 2-hydroxyethyl analogue (46), which possess several of the structural features of the antibiotic bicyclomycin, have been synthesized by a route involving construction of the piperazine-2,5-dione ring at a late stage in the reaction sequence. Treatment of ethyl 3-(2-methoxyethyl)-3-methylglycidate with acetic anhydride and sulfuric acid gives ethyl 2-acetoxy-3-(2-methoxyethyl)-3-butenoate (10), which is converted to the corresponding carboxylic acid by ethanolysis, hydrolysis, and reacetylation. This, on conversion to its acid chloride and reaction with N,N′-dibenzylglycinamide, gives 2-acetoxy-N-benzyl-N-(2-benzylamino-2-oxocthyl)-3-(2methoxyethyl)-3-butenamide (21). Compound 21, on hydrolysis and oxidation, gives the corresponding 2-oxo compound, which on treatment with magnesium isopropylcyclohexylamide followed by acetylation yields 32. Demethylation of 21 with alkylthiotrimethylsilanes gives the corresponding 2-hydroxyethyl compound, whose tetrahydropyranyl ether on subjection to the above reaction sequence gives the 2-(tetrahydropyran-2-yloxy)ethyl analogue of 32. This, on hydrolysis, gives a 3: 1 mixture of compound 46 and a spiro compound formed by displacement of the acetoxyl group by the hydroxyl oxygen atom of 46.
3-乙酰氧基-1,4-二苄基-3-[1-(2-甲氧基乙基)乙烯基]哌嗪-2,5-二酮(32)及其2-羟乙基类似物(46),具有抗生素双环霉素的几个结构特征,通过在反应序列后期构建哌嗪-2,5-二酮环的路线合成。将乙基3-(2-甲氧基乙基)-3-甲基缩水甘油酸酯与乙酸酐和硫酸处理得到乙基2-乙酰氧基-3-(2-甲氧基乙基)-3-丁烯酸酯(10),通过乙醇解、水解和再乙酰化转化为相应的羧酸。将其转化为酸酐并与N,N′-二苄基甘氨酰胺反应,得到2-乙酰氧基-N-苄基-N-(2-苄胺基-2-氧辛基)-3-(2-甲氧基乙基)-3-丁烯酰胺(21)。化合物21经水解和氧化得到相应的2-氧代化合物,再与异丙基环己基胺镁处理后进行乙酰化,得到32。用烷基硫三甲基硅烷对21进行脱甲基化得到相应的2-羟乙基化合物,其四氢吡喃基醚经上述反应序列得到32的2-(四氢吡喃-2-基氧基)乙基类似物。经水解后得到化合物46与由46的乙酰氧基被羟基氧原子取代形成的螺环化合物3:1混合物。