Synthesis of (S)‐N^τ‐[D₃] methylhistidine

Abstract

S)-Histidine methyl ester was converted on a 20 g scale to its NU, N T -cyclic urea by treatment with carbonyl diimidazole. The N T position was alkylated with [D3]-methyl iodide and the product was hydrolyzed to give isomerically and isotopically pure W -LO3] methylhistidine, without significant loss of optical activity. Key words : deuteri um, carbonyl di imidazole, (S)-5-0~0-7-carbomethoxy-5,6,7,8tetra hydr o imi dazo 1.1 , 5-c I pyr i mi d i ne , ( S ) -N T-met hy 1 hi st i d i ne .

Synthetic approaches to regiospecifically mono‐ and dilabelled arenes

“…Alternative routes of elaboration from [1‐ 13 C]cyclohexanone include cyanohydrin formation, followed by dehydration and aromatisation to give benzonitrile. Subsequent hydrolysis provides [1‐ 13 C]benzoic acid (Scheme ) 170…”

Synthesis of Stable Isotope Labeled 13C4-1,4-Dihydropyridines on 5,6-Position and Its Substituent Carbon

“…1.1 13 C 4 -乙酰乙酸酯的合成讨论 当前报道的 13 C 标记的乙酰乙酸酯的合成方法有克 莱森缩合法(Scheme 2, A) [21][22] 、克莱森缩合改进法 (Scheme 2, B) [23] 、丙二酸法(Scheme 2, C) [24] 、双烯酮法 (Scheme 2, D) [19] 以及乙酰咪唑的克莱森缩合酯化法 (Scheme 2, E) [20] . 克莱森缩合法和丙二酸法产率较低, 仅为 65%; 双烯酮法受到 13 [25] 、醋酸铵 [26][27] 、氨水 [28][29][30] 、 碳酸铵 [31] 、碳酸氢铵 [32] 、氨基甲酸铵 [33] 等.…”