21-May-2013
02:11:14 IST
|
NISCAIR ONLINE PERIODICALS REPOSITORY (NOPR) >
NISCAIR PUBLICATIONS >
Research Journals >
Indian Journal of Chemistry -Section B (IJC-B) >
IJC-B Vol.44B [2005] >
IJC-B Vol.44B(09) [September 2005] >
| Title: | Nitrogen ligands: The transition metal catalyzed reaction of aryl halides with olefins (Mizoroki-Heck), phenylboronic acid (Suzuki coupling) and Buchwald-Hartwig amination, new catalysts and effect of co-catalysts — Aryl halide activation — Part I |
| Authors: | Iyer, Suresh
Kulkarni, Girish M
Ramesh, C
Sattar, Aruna K |
| Keywords: | Nitrogen ligands
Mizoroki-Heck reaction
DMG
DAB
palladacycle |
| Issue Date: | Sep-2005 |
| Publisher: | CSIR |
| IPC Code: | Int.Cl.7 C 07 C, C 07 D |
| Abstract: | Nitrogen ligands are an excellent alternative for the traditional
P-ligands in the Pd catalyzed Mizoroki-Heck reaction, Suzuki coupling and
Buchwald-Hartwig aryl amination. Pd complexes of dimethyl glyoxime,
8-hydroxyquinoline, salen, picolinic acid, and DAB ligands gave high yields of
the E-cinnamates and E-stilbenes from aryl iodides. Acetophenone
oxime N, N-dimethybenzylamine and ferrocenyl oxime palladacycle are better
catalysts with comparable yields, high TON (95, 000) and TOF's (2, 500 h-1) to P-ligand catalysts. Aryl bromides and
in a few cases, aryl chlorides could also be activated by these complexes by
the use of Lewis acid and (C4H9)4NI as
additives. Cy-DAB ligands gave good yields with electron rich aryl bromides and
the use of ionic liquid improve the yield. These N-ligand metal complexes can
be readily synthesized and the ligands possess the advantage of easy functional
group modifications and convenient synthetic methods compared to P-ligands. The
degradation reactions associated with P-ligands are not observed in the
N-ligands, with comparable, high thermal, moisture and air stability and
insensitivity. Activation of aryl bromides (Mizoroki-Heck reaction, Suzuki reaction)
could be achieved in high yields, TON and TOF (86-94% yield, TON: 36, 000-90,
000, TOF: 6, 000-11, 500 h-1) catalyzed by monomeric amine and oxime
palladacycles (Cat-8, 11, 13 B) with a N-heterocyclic carbene ligand
better than a phosphorous ligand. Molten (C4H9)4NBr
is an efficient ionic liquid medium for the Mizoroki-Heck reaction of aryl
bromides, giving higher yields. Low to moderate yields of aryl amination are
obtained with the carbene palladacycle and N, N-dibenzyl piperazine Pd
complexes. |
| Page(s): | 1894-1908 |
| ISSN: | 0975-0983(Online); 0376-4699(Print) |
| Source: | IJC-B Vol.44B(09) [September 2005]
|
|
