Synthesis of a Tetrahydropyran NK<sub>1</sub> Receptor Antagonist via Asymmetric Conjugate Addition
作者:Mark A. Huffman、Jacqueline H. Smitrovich、Jonathan D. Rosen、Geneviève N. Boice、Chuanxing Qu、Todd D. Nelson、James M. McNamara
DOI:10.1021/jo0504161
日期:2005.5.1
1-[2-(R)-1-(R)-[3,5-bis(trifluoromethyl)phenyl]ethoxy}-3-(R)-(3,4-difluorophenyl)-4-(R)-tetrahydro-2H-pyran-4-ylmethyl]-3-(R)-methylpiperidine-3-carboxylic acid (1) were developed. In both routes, the core tetrahydropyran stereochemistry was established by asymmetric conjugate addition to an α,β-unsaturated ester (6), using an amide of the chiral auxiliary pseudoephedrine. Selective ester reduction
NK 1受体拮抗剂1- [2-(R)-1-(R)-[3,5-双(三氟甲基)苯基]乙氧基} -3-(R)-(3,4-)的两个不对称合成开发了二氟苯基)-4-(R)-四氢-2 H-吡喃-4-基甲基] -3-(R)-甲基哌啶-3-羧酸(1)。在这两种途径中,使用手性辅助伪麻黄碱的酰胺,通过向α,β-不饱和酯(6)进行不对称共轭加成,建立了核心四氢吡喃立体化学。然后选择性酯还原允许形成具有热力学上优选的反式几何结构的内酯2。手性醚侧链(3)通过立体选择性缩醛取代连接。在第一途径中,通过N-烷基化将手性哌啶酯片段安装在末端。在较短的第二个合成中,此乐曲一开始被附加到迈克尔接受器上。