Synthesis of HR 916 K: An Efficient Route to the Pure Diastereomers of the 1-(Pivaloyloxy)ethyl Esters of Cephalosporins
作者:Elisabeth Defoßa、Gerd Fischer、Uwe Gerlach、Rolf Hörlein、Dieter Isert、Norbert Krass、Rudolf Lattrell、Ulrich Stache、Theo Wollmann
DOI:10.1002/jlac.199619961107
日期:1996.11
HR 916 K (5), the 1-(S)-(pivaloyloxy)ethyl prodrug ester of the cephalosporin cefdaloxime, exhibits a significantly higher oral bioavailability than the 1-(R) diastereomer HR 916 J. An efficient synthesis of HR 916 K was developed. The separation of the diastereomers was achieved by precipitation of the 1-(R)-hydrochloride 9 followed by crystallization of the 1-(S)-amine 10 (de > 96%). The 1-(R) diastereomer
HR 916 K(5)是头孢菌素头孢达肟的1-(S)-(新戊酰氧基)乙基前药酯,其口服生物利用度明显高于1-(R)非对映异构体HR 916J。HR 916 K的有效合成发展了。非对映异构体的分离通过沉淀1-(R)-盐酸盐9,然后结晶1-(S)-胺10(de> 96%)来实现。通过酸性皂化或酶促裂解将1-(R)非对映异构体9再循环至AMCA(7)。胺10用巯基苯并噻唑硫酯或由羧酸13和14制备的混合酸酐将其酰化,几乎可以定量收率。肟的脱保护和甲苯磺酸酯的形成是一步进行的。使用硫酯18,我们以42%的收率从AMCA(7)获得了HR 916 K(5)。