Pd–Phosphine Precatalysts for Modern Cross-Coupling Reactions - New Trends in Cross-Coupling: Theory and Applications - page 113

Br

CO 2 H

N 0.1 mol% [ p -Me 2 NC 6 H 4 ( t -Bu) 2 P] 2 PdCl 2

N

N

N
H

O

+

F N

N
H

O

F

K 3 PO 4 , i -PrOH/H 2 O
85 C, 93 %

F (HO) 2 B CO 2 H

F

2 kg scale

H
N

N

O

N

N
H

O

F

F

Scheme 3.21 Large-scale [p-Me 2 NC 6 H 4 (t-Bu) 2 P] 2 PdCl 2 -catalyzed Suzuki-Miyaura
coupling reaction.

ArCHO + Et 3 SiX

P Sol

Sol

Pd

ArH

P

Et 3 SiH

P H

Ar

P X

COAr

Pd Pd

Ar-X

P P

Et 3 SiX

P X

Ar

Pd

P

CO

Et 3 SiH

Scheme 3.22 Proposed catalytic cycle for carbonylation using dcppPdCl 2 .

acetone

Cy 2 P PCy 2

(COD)PdCl 2 + Cy 2 P 2

Pd

rt

Cl Cl

Barnard 2008

Scheme 3.23 Preparation of dcppPdCl 2 . 89

strengthens the CO binding to Pd and hence retards its insertion into the
Pd-Ar bond after the oxidative addition step (Scheme 3.22). However, to
promote the oxidative addition of Ar-Cl, an electron-rich bulky ligand co-
ordinated to the Pd catalyst is needed. By careful choice of a ligand, this
transformation can, however, be successfully carried out. Barnard and co-
workers employed the L 2 PdX 2 precatalyst dichloro[1,3-bis(dicyclohexylpho-
sphino)propane]palladium(II) 87 (Scheme 3.23) in the carbonylation of a
range of less challenging aryl chlorides. 88 This process is discussed in more
detail in Chapter 9.