Introduction to New Trends in Cross-Coupling - New Trends in Cross-Coupling: Theory and Applications - page 12

Concurrently, Heck demonstrated independently the Pd-catalyzed reaction
of aryl halides with alkenes in the presence of a hindered amine base. 31
Heck's work on aryl and vinyl halide substrates led to the second most
practiced reaction in cross-coupling, namely the Mizoroki-Heck reaction. 32
Irina Beletskaya and Andrei Cheprakov in Chapter 9 discuss the role of
modern Heck reactions in organic synthesis.
So far, only simple metal salts had been employed as catalysts. Corriu and
Masse 33 and Tamao and Kumada 34 independently described the nickel-
catalyzed coupling reaction of Grignard reagents with aryl halides. Tamao
and Kumada (Figure 1.8) thereby pioneered the area of cross-coupling by
showing the effects of adding phosphine ligands to the catalysts. 33-35
The benefit of using phosphine ligands was particularly striking in re-
actions with less reactive aryl chlorides. Chapter 2, authored by Andrew
DeAngelis and Thomas Colacot, covers the emergence of the development and
use of ligands in Pd-catalyzed cross-coupling reactions in detail, with some
theoretical background in choosing the right ligands for specific reaction
types. Only during the past 10-15 years has the importance of the steric and
electronic properties of the ligands used been fully recognized and evaluated.
A few years after Tamao and Kumada's disclosure of the importance
of added phosphine ligands, four groups made independent reports on
the cross-coupling reactions between alkynes and C(sp 2 )-halide
reagents. 36 Cassar made use of Pd(PPh 3 ) 4 as catalyst, whereas Heck
and Sonogashira (Figure 1.9) used Pd(PPh 3 ) 2 (OAc) 2 and Pd(PPh 3 ) 2 Cl 2 ,
Figure 1.8 Prof. Makoto Kumada.
Photograph courtesy of Kyoto University.