Well-defined Al-containing Lewis acids for organic transformations

Abstract

This thesis focuses on designing and catalytic applications of aluminum based Lewis acids. It contains four parts: Chapter 1 gives a brief introduction of the development of Lewis acid chemistry and its increasing influence on modern synthetic organic chemistry. Aluminum compounds are widely used as efficient and powerful Lewis acid catalysts. Hence, we proposed our strategy to prepare various Al-based Lewis acids and investigate their potential applications.

Chapter 2 describes the design, synthesis and characterization of a series of aluminum bistriflate complexes supported by β-diketiminate ligands. Several approaches to cationic aluminum complexes were also illustrated in this chapter.

Chapter 3 focuses on the catalytic application of these aluminum bistriflate complexes on Diels-Alder transformations. Less reactive dienes such as 2,3-dimethylbutadiene, 1,3-cyclohexadiene and isoprene and a series of dienophiles were examined. A competition between Diels-Alder reaction and Michael polymerization was also described when cyclic dienophiles were used.

Chapter 4 describes the synthesis of several aluminum compounds stabilized by an NCN pincer ligand. Several experiments indicated that the cationic aluminum complex 50 was the active species for Diels-Alder catalytic reactions.