Palladium-catalyzed direct functionalization of benzoxazoles with alkenyl iodides
摘要:
A straightforward procedure for the palladium-catalyzed direct functionalization of benzoxazoles with alkenyl iodides is described. The reactions employ a Pd(II)-precatalyst and use 'on water' conditions to achieve the ready union of a range of di- and tri-substituted alkenyl iodides with a small range of benzoxazoles. (C) 2012 Elsevier Ltd. All rights reserved.
CuCl-catalyzed C2-alkenylation reaction of benzoxazoles with allyl halides has been established. The distinctive features of this protocol include the use of an inexpensive copper salt as catalyst, simple and readily available starting materials, and ligand-free conditions. An important application of this method to the synthesis of 1,3-diene substituted benzoxazoles has also been achieved.
A catalytic system comprised of Pd(OAc)2 and bidentate ligand dppe enabled first direct arylations with moisture-stable aryl sulfamates as electrophiles, and proved applicable to unprecedented C−H bond functionalizations with easily accessible alkenyl phosphates as well as benzyl phosphates.
Nickel promoted switchable hydroheteroarylation of cyclodienes via C–H bond activation of heteroarenes
作者:Wei-Chih Lee、Wei-Chin Shih、Ting-Hsuan Wang、Yuhua Liu、Glenn P.A. Yap、Tiow-Gan Ong
DOI:10.1016/j.tet.2015.03.066
日期:2015.7
hydroheteroarylation of cyclicdienes via C–H bond activation of heteroarenes. In the presence of an N-heterocyclic carbene (NHC) ligand, hydroheteroarylation of cyclicdiene with azole afforded α-alkenyl-azole, forging a Heck-like product without using any external oxidant. Conversely, changing the ligand to PCy3 would switch this reaction manifold to afford the other isomeric β-alkenyl substituted azole.