Asymmetric Synthesis of Neolignans (−)-<i>epi</i>-Conocarpan and (+)-Conocarpan via Rh(II)-Catalyzed C−H Insertion Process and Revision of the Absolute Configuration of (−)-<i>epi</i>-Conocarpan
作者:Yoshihiro Natori、Hideyuki Tsutsui、Naoki Sato、Seiichi Nakamura、Hisanori Nambu、Motoo Shiro、Shunichi Hashimoto
DOI:10.1021/jo900502d
日期:2009.6.5
Catalytic asymmetric synthesis of neolignan natural products (−)-epi-conocarpan and (+)-conocarpan has been achieved by exploiting an enantio- and diastereoselective intramolecular C−H insertion reaction to construct a cis-2-aryl-2,3-dihydrobenzofuran ring system as a key step. The C−H insertion reaction of 5-bromoaryldiazoacetate catalyzed by Rh2(S-PTTEA)4, a new dirhodium(II) carboxylate complex that
通过利用对映选择性和非对映选择性分子内CH插入反应构建顺式-2-芳基-2,3-二氢苯并呋喃,实现了新木脂素天然产物(-)-表-锥果和(+)-锥果的催化不对称合成环系统作为关键步骤。由 Rh 2 ( S -PTTEA) 4催化的 5-溴芳基重氮乙酸酯的 C-H 插入反应,这是一种新的羧酸二铑 (II) 配合物,它结合了N-邻苯二甲酰基-( S )-丙氨酸三乙基酯作为手性桥接配体,提供了 2-芳基- 5-溴-3-甲氧基羰基-2,3-二氢苯并呋喃具有极高的非对映选择性(顺式/反式)= 97:3)和顺式异构体的高对映选择性(84% ee)。