Highly Efficient Cyclization ofo-Iodobenzoates with Aldehydes Catalyzed by Cobalt Bidentate Phosphine Complexes: A Novel Entry to Chiral Phthalides
作者:Hong-Tai Chang、Masilamani Jeganmohan、Chien-Hong Cheng
DOI:10.1002/chem.200601880
日期:2007.5.18
corresponding phthalide derivative 3 u. This synthetic method is compatible with a variety of functional groups on the aryl ring of 2. The high efficiency of the cobalt catalyst containing a dppe (dppe=1,2-bis(diphenylphosphino)ethane) ligand encouraged us to investigate the asymmetric version of the present catalytic reaction by employing bidentate chiral ligands. Thus, aromatic aldehydes 2 a-c, 2 f
2-碘苯甲酸甲酯1 ac与各种芳香醛进行2 am的环化反应(RC6H4CHO:R = H 2 a,4-CH3 2 b,4-tBu 2 c,4-OMe 2 d,3-OMe 2 e,4- Cl 2 f,4-CF3 2 g,4-CN 2 h,4-Ph 2 i;苯并[d] [1,3]二恶唑-5-甲醛(2 j),1-萘甲醛(2 k),苯并呋喃在[CoI2(dppe)](dppe = 1,2-双(二苯基二膦基)乙烷)和Zn粉在无水四氢呋喃中于75°C存在下于-2-甲醛(2 l)和异烟碱醛(2 m)) 24小时后,以良好至优异的产率得到相应的邻苯二甲酸酯衍生物3am和3qt。在相似的反应条件下,反应性较低的脂族醛,庚醛(2 n),丁醛(2 o)和2-苯基乙醛(2 p)也分别以1 a进行环化反应,以提供3 np的收率,以公平至良好的收率。催化反应可以进一步用1 a扩展到肉桂醛(2 q),得到相应的邻苯二甲酸酯衍生物3