Studies towards the synthesis of the fluorescent bases of phenylalanine transfer ribonucleic acids: Synthesis of 7-(2-Hydroxy-3-methylbutyl)wye, a model for the minor base isolated from rat liver.
作者:Taisuke ITAYA、Akemi MIZUTANI、Nobuhide WATANABE
DOI:10.1248/cpb.37.1221
日期:——
Treatment of 1-benzyl-7-(hydroxymethyl)wye (8) with PBr3 in the presence of Ph3P gave the phosphonium bromide 9 in good yield, Heating 9 and Me2 CHCHO (7) in MeOH in the presence of K2CO3 provided 1-benzyl-1, 4-dihydro-4, 7-dimethyl-6-(3-methyl-1-butenyl)-9H-imidazo[1, 2-a]purin-9-one (11), a positional isomer of the objective 1-benzyl-7-(3-methyl-1-butenyl)wye (5), as a major product. When the reaction was conducted in Me2NCHO at -65°C using n-BuLi as base, a 7 : 2 mixture of (E)-and (Z)-5 was obtained in good yield. Nevertheless, neither the protected amino aldehyde 18 nor 21 gave the desired olefin under similar conditions, implying poor applicability of this method to the synthesis of the fluorescent bases of phenylalanine transfer ribonucleic acids (tRNAsPhe).Compound 5 was alternatively synthesized by the Wittig reaction between 1-benzyl-7-formylwye (3) and Ph3P+CH2CHMe2 I- (4) in tetrahydrofuran as an equimolar mixture of the geometrical isomers in 50% yield. When the reaction was carried out in Me2SO at room temperature using two equivalents each of NaCH2SOMe and 4, the product, obtained in high yield, was (E)-11. The use of an equimolar amount of the base afforded (E)-5 in 26% yield. Oxidation of (E)-5 with OsO4 followed by hydrogenolysis over Pd-C gave 7-(2-hydroxy-3-methylbutyl)wye (2), a model for the minor base from rat liver tRNA.Phe.
在 Ph3P 存在下,用 PBr3 处理 1-苄基-7-(羟甲基)碱 (8),得到溴化鏻 9,收率很高;在 K2CO3 存在下,在 MeOH 中加热 9 和 Me2 CHCHO (7),得到 1-苄基-1、4-二氢-4, 7-二甲基-6-(3-甲基-1-丁烯基)-9H-咪唑并[1, 2-a]嘌呤-9-酮 (11)的主要产物,它是客观存在的 1-苄基-7-(3-甲基-1-丁烯基)wye (5)的位置异构体。当以 n-BuLi 为碱在 Me2NCHO 中于 -65°C 进行反应时,可获得 7 : 2 的 (E)-5 和 (Z)-5 混合物,收率很高。在类似条件下,受保护的氨基醛 18 和 21 都没有得到所需的烯烃,这表明该方法在合成苯丙氨酸转移核糖核酸(tRNAsPhe)的荧光碱基方面的适用性较差。化合物 5 是通过 1-苄基-7-甲酰基黑麦草(3)和 Ph3P+CH2CHMe2 I- (4)在四氢呋喃中的 Wittig 反应合成的,为几何异构体的等摩尔混合物,收率为 50%。在室温下于 Me2SO 中使用 NaCH2SOMe 和 4 各两当量进行反应时,得到的高产率产物为 (E)-11。使用等摩尔量的碱得到(E)-5,收率为 26%。用 OsO4 氧化 (E)-5,然后在 Pd-C 上进行氢解,得到了 7-(2-羟基-3-甲基丁基)wye (2),这是大鼠肝脏 tRNA.Phe 小碱基的模型。