Cross-coupling reactions materials science applications

A novel series of 2,5-disubstituted boryl thiazoles 10 is prepared by means of Hantzsch cyclizations of thioamides with monohalogenated boryl aldehydes 9a/b (14JA17669).These aldehydes are derived from the unsubstituted a-MIDA boryl aldehyde 8 by means of electrophilic halogenation (NBS or NCS, pyrrolidine). Application of these novel boryl thiazoles 10 is demonstrated in cross-coupling reactions (e.g., 11-12). The optimal coupling conditions utilize the Lipshutz surfactant TPGS-750-M in water. The 2,5-disubstituted boryl thiazole intermediate 10 is a versatile intermediate for medicinal chemistry and material science. 

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. 

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