Enzymatic- and Iridium-Catalyzed Asymmetric Synthesis of a Benzothiazepinylphosphonate Bile Acid Transporter Inhibitor
作者:David J. Cowan、Jon L. Collins、Mark B. Mitchell、John A. Ray、Peter W. Sutton、Amy A. Sarjeant、Eric E. Boros
DOI:10.1021/jo402311e
日期:2013.12.20
A synthesis of the benzothiazepine phosphonic acid 3, employing both enzymatic and transition metal catalysis, is described. The quaternary chiral center of 3 was obtained by resolution of ethyl (2-ethyl)norleucinate (4) with porcine liver esterase (PLE) immobilized on Sepabeads. The resulting (R)-amino acid (5) was converted in two steps to aminosulfate 7, which was used for construction of the benzothiazepine
描述了同时使用酶催化和过渡金属催化的苯并噻氮平膦酸3的合成。通过用固定在Sepabeads上的猪肝酯酶(PLE)拆分(2-乙基)去甲亮氨酸乙酯(4),可以得到3的四级手性中心。分两步将所得的(R)-氨基酸(5)转化为氨基硫酸盐7,该氨基硫酸盐7用于构造苯并噻氮平环。由三甲基氢醌11分四个步骤制备的苯甲酮15使磷(Arbuzov化学)和硫(Pd(0)催化的硫醇偶联)的顺序引入成为了硫醇中间体18。用氨基硫酸盐7进行18的S-烷基化,然后进行环脱水,得到二氢苯并硫氮杂pine 20。铱在[Ir(COD)2 BArF](26)和Taniaphos配体P的配合物中催化的20的不对称氢化反应提供了(3 R,5 R)-四氢苯并硫氮杂卓30。将30氧化为砜31并进行膦酸酯水解,完成12个步骤中3的合成,总产率为13%。