Parmentier G G, Busson R H, Janssen G A, Mannaerts G P, Eyssen H J
Laboratory of Microbiology, Faculteit Geneeskunde, Katholieke, Universiteit Leuven, Belgium.
Steroids. 1993 Aug;58(8):351-6. doi: 10.1016/0039-128x(93)90037-n.
The synthesis and 14C-labeling of 3 alpha, 7 alpha, 12 alpha-trihydroxy-27-carboxymethyl-5 beta-cholestan-26-oic acid by two different approaches is described. One of them involves chain elongation of cholic acid via Wittig-Horner condensation of its formylated 24-aldehyde with tetraethyl phosphonoglutarate. The resulting cholestenoate, on deprotection and hydrogenation, affords the unusual C29 bile acid in good yield. An alternative procedure consists in a malonic ester synthesis starting from the formylated 24-alcohol which, after conversion into a mesylate, is reacted with sodium salt of 2-carboethoxy-gamma-butyrolactone. Alkaline hydrolysis, decarboxylation, esterification with diazomethane and selective tosylation of the newly introduced primary hydroxyl function give a C28 precursor, which is easily chain-elongated into a labeled or unlabeled C29 bile acid by reaction with cyanide and hydrolysis. Due to the easy lactonization of some of the C28 intermediates, the latter method provides a better way for introducing a C-29 label than the sequence usually employed for carboxyl labeling of bile acids and consisting in a decarboxylative halogenation of the parent acid followed by substitution of the norhalogenide with [14C]cyanide and hydrolysis. The structure of the synthesized acid or its dimethyl ester is confirmed by 13C nuclear magnetic resonance spectroscopy and mass spectrometry, and is also shown by gas liquid chromatography to be identified with an authentic sample of biosynthetic C29 dioic bile acid extracted from body fluids of Zellweger patients.
描述了通过两种不同方法合成3α,7α,12α-三羟基-27-羧甲基-5β-胆甾烷-26-酸并进行¹⁴C标记的过程。其中一种方法涉及通过胆酸的24-甲酰化醛与四乙基膦酰戊二酸的Wittig-Horner缩合反应使胆酸进行链延长。所得的胆甾烯酸经脱保护和氢化后，以良好的产率得到了不寻常的C29胆汁酸。另一种方法是从24-甲酰化醇开始进行丙二酸酯合成，该醇在转化为甲磺酸酯后，与2-乙氧羰基-γ-丁内酯的钠盐反应。碱性水解、脱羧、用重氮甲烷酯化以及对新引入的伯羟基进行选择性甲苯磺酰化得到一个C28前体，该前体通过与氰化物反应并水解可轻松地链延长为标记或未标记的C29胆汁酸。由于一些C28中间体易于内酯化，后一种方法为引入C-29标记提供了一种比通常用于胆汁酸羧基标记的序列更好的方法，该序列包括母体酸的脱羧卤化，随后用[¹⁴C]氰化物取代去卤化物并水解。合成酸或其二甲酯的结构通过¹³C核磁共振光谱和质谱得到证实，并且通过气液色谱法也表明与从Zellweger患者体液中提取的生物合成C29二酸胆汁酸的真实样品一致。
