The synthesis of tetradecanoic acid enriched with 13C at carbons 1, 3, or 6 is described. The label at the carbonyl carbon was introduced by treating 1-bromotridecane with K13CN (90% enriched) to form the 13C-labeled nitrile, which upon hydrolysis yielded the desired acid. The [3-13C]tetradecanoic acid was synthesized by alkylation of diethyl sodio-malonate with [1-13C]1-bromododecane; the acid was obtained upon saponification and decarboxylation. The label at the 6 position was introduced by coupling the appropriately labeled alkylcadmium chloride with the half acid chloride methyl ester of the appropriate dioic acid, giving the corresponding oxo fatty acid ester. Formation of the tosylhydrazone of the oxo-ester followed by reduction with sodium cyanoborohydride gave the labeled methyl tetradecanoate which, upon hydrolysis, yielded the desired tetradecanoic acid. All tetradecanoic acids were identical to unlabeled analogs as evaluated by gas-liquid chromatography and infrared or NMR spectroscopy. These labeled fatty acids were used subsequently to prepare the correspondingly labeled diacyl phosphatidylcholines.

中文翻译：

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碳13标记的十四烷酸的合成。

描述了在13、3或6个碳原子上富含13C的十四烷酸的合成。通过用K13CN（浓缩90％）处理1-溴十三烷，引入羰基碳上的标记，形成13C标记的腈，水解后生成所需的酸。通过用[1-13C] 1-溴十二烷将苏二-丙二酸二乙酯烷基化来合成[3-13C]十四酸。通过皂化和脱羧获得酸。通过将适当标记的烷基镉与适当的二酸的半酰氯甲基酯偶联，引入6位标记，得到相应的含氧脂肪酸酯。形成羰基酯的甲苯磺酰基zone，然后用氰基硼氢化钠还原，得到标记的十四烷酸甲酯，水解后，得到所需的十四烷酸。通过气-液色谱法和红外或NMR光谱法评估，所有十四烷酸均与未标记的类似物相同。这些标记的脂肪酸随后用于制备相应标记的二酰基磷脂酰胆碱。