Oxime-derived, chloro-bridged palladacycles 16 are efficient complexes for the Heck vinylation of aryl halides. The isolated catalysts are thermally stable, not sensitive to air or moisture and easily accessible from inexpensive starting materials. The reaction can be performed under aerobic conditions, with aryl iodides, bromides and chlorides with acrylic esters and olefins displaying turnover numbers (TON) of up to 10(10) for phenyl iodide and turnover frequencies (TOF) of 1.4 x 10(8) h(-1). Deactivated aryl bromides undergo the Heck reaction with styrene with TON and TOF values up to 97,000 and 6063 h-1, respectively. Even aryl chlorides undergo the coupling reaction with olefins with TON up to 920. Complexes 16 catalyze the synthesis of 2,3-disubstituted indenones and indoles in good yields via annulation reaction of internal alkynes with o-bromo- or o-chlorobenzaldehyde and o-iodoaniline, respectively.
Controlling Olefin Isomerization in the Heck Reaction with Neopentyl Phosphine Ligands
作者:Matthew G. Lauer、Mallory K. Thompson、Kevin H. Shaughnessy
DOI:10.1021/jo501840u
日期:2014.11.21
The use of neopentyl phosphine ligands was examined in the coupling of aryl bromides with alkenes. Di-tert-butylneopentylphosphine (DTBNpP) was found to promote Heck couplings with aryl bromides at ambient temperature. In the Heck coupling of cyclic alkenes, the degree of alkene isomerization was found to be controlled by the choice of ligand with DTBNpP promoting isomerization to a much greater extent than trineopentylphosphine (TNpP). Under optimal conditions, DTBNpP provides high selectivity for 2-aryl-2,3-dihydrofuran in the arylation of 2,3-dihydrofuran, whereas TNpP provided high selectivity for the isomeric 2-aryl-2,5-dihydrofuran. A similar complementary product selectivity is seen in the Heck coupling of cyclopentene. Heck coupling of 2-bromophenols or 2-bromoanilides with 2,3-dihydrofurans affords 2,5-epoxybenzoxepin and 2,5-epoxybenzazepins, respectively.
[Pd/Base/QX] catalyst systems for directing Heck-type reactions
作者:Tuyet Jeffery、Marc David
DOI:10.1016/s0040-4039(98)01135-6
日期:1998.8
Palladium-catalyzed arylation of 2,3-dihydrofuran can be directed at will by an appropriate selection of the [Pd/Base/QX] catalyst systems, (C) 1998 Elsevier Science Ltd. All rights reserved.
A Versatile Catalyst for Heck Reactions of Aryl Chlorides and Aryl Bromides under Mild Conditions
作者:Adam F. Littke、Gregory C. Fu
DOI:10.1021/ja010988c
日期:2001.7.1
for Heck reactions of arylchlorides and bromides. A sterically and electronically diverse array of aryl bromides, as well as activated arylchlorides, couple with a range of mono- and disubstituted olefins at room temperature, furnishing the arylated product with high E/Z stereoselection. The corresponding reactions of a broad spectrum of electron-neutral and electron-rich arylchlorides proceed at