Cross-coupling reactions structural properties

Phosphine oxides have been extensively employed as ligands in transition-metal catalyzed cross-coupling reactions. However, their property to act as a structural mimic of carboxylate ions make them important preligands in C-H bond activation. Ackermann and co-workers have... 

The easy accessibility to a variety of different structures and, consequently, to molecules with different chemical and physical properties, justifies the potential application of POMs in different fields, from material science, to medicinal chemistry and homogeneous/heterogeneous catalysis. Catalytic applications of POMs have been systematically studied since the late 1970s. POMs have been known mainly as Brpnsted acids, but their structural diversity and the merging with different catalytic domains has expanded their application to include hydrogenations, click chemistry, and cross-couplings reactions.However, due to their thermal and oxidative stabilities, POMs still retain a major appeal as oxidation catalysts. Relevant structures of some POMs that will be described in this chapter are summarized in Fig. 21.1. 

Synthesis of Polyynes. Conjugated diyne and polyyne units, which exhibit unusual electrochemical, optical, and structural properties, can be efficiently constructed from 1-haloalkynes via homologation by one acetylene unit with TIPS-acetylene through a transition metal-catalyzed cross-coupling reaction, 2 which allows an access to a new class of polyyne framework. 

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