Jia Yanxing, Zhu Jieping
Institut de Chimie des Substances Naturelles, CNRS, 91198 Gif-sur-Yvette Cedex, France.
J Org Chem. 2006 Sep 29;71(20):7826-34. doi: 10.1021/jo061471s.
One-pot synthesis of indoles by a palladium-catalyzed annulation of ortho-haloanilines and aldehydes has been developed. Coupling of ortho-iodoaniline with aldehyde is realized under mild ligandless conditions [Pd(OAc)2, DABCO, DMF, 85 degrees C], whereas X-Phos is found to be the ligand of choice for coupling reactions involving ortho-chloroanilines/ortho-bromoanilines and aldehydes. A variety of ortho-haloanilines with different electronic properties are suitable substrates, and aldehydes including chiral ones participated in this reaction without racemization. Coupling of (S)-2-N,N-di-tert-butoxycarbonyl-5-oxopentanoate, derived from L-glutamic acid, with ortho-haloanilines provides a rapid access to the ring-A-substituted tryptophans in good to excellent yields.
已开发出通过钯催化邻卤代苯胺与醛的环化反应一锅法合成吲哚。邻碘苯胺与醛的偶联在温和的无配体条件下（[Pd(OAc)₂、DABCO、DMF、85℃]）实现，而发现X-Phos是涉及邻氯苯胺/邻溴苯胺与醛的偶联反应的首选配体。各种具有不同电子性质的邻卤代苯胺都是合适的底物，包括手性醛在内的醛参与该反应且不会发生外消旋化。由L-谷氨酸衍生的(S)-2-N,N-二叔丁氧羰基-5-氧代戊酸酯与邻卤代苯胺的偶联反应能够以良好至优异的产率快速合成A环取代的色氨酸。
