New Chemistry of Lithium Trimethylsilyldiazomethane & Development of Novel Amination Reactions

This thesis contains two parts. Part I is about the development of novel α-amination of carbonyl compounds using lithium trimethylsilyldiazomethane and its application to the natural product syntheses, which is comprised of first four chapters. Part II is about the preparation of α-silyl ketones and the C(sp3)–H amination of the silylated cyclopropenes, which are described in the chapter 5 and the chapter 6. In the four chapters of Part I, the chapter 1 surveys briefly the recent development in the lithium trimethylsilyldizaomethane chemistry and the general ways of achieving α-amination of carbonyl compounds. The chapter 2 depicts the formal [3+2] cycloadditions of α,β-unsaturated cyclic ketones with lithium trimethylsilyldiazomethane to synthesize a variety of the pyrazolines and pyrazoles. Selected examples are highlighted to demonstrate the reaction scope and limitations. The chapter 3 demonstrates the development of the novel α-amino-β-cyanation of unsaturated carbonyl compounds. Also the application of this methodology is described in the chapter 4 in the context of pursuing the total synthesis of marine natural product amathaspiramide C and the synthetic approaches towards the pyrrole-imidazole alkaloid massadine. In Part II, the chapter 5 discloses an efficient way to synthesize the α-silylated ketones from the reaction of aldehydes with trimethylsilyldiazomethane in the presence of a catalytic amount of InCl3 and its synthetic utility to silylated cyclopropenes. The chapter 6 describes an unprecedented C(sp3)–H amination reaction of the silylated cyclopropenes, which is believed to proceed through the initial regioselective Alder-ene reaction followed by a site-selective allylic C–N bond transposition.