| New reactivity patterns of methylenecyclopropanes (MCPs) have been disclosed particularly regarding the generation of a synthetically useful enolate intermediate via ring cleavage of monoactivated MCPs.; Chapter I reviews the general reactivity patterns of methylenecyclopropanes.; In Chapter II, MgI2-mediated ring expansions of MCP amides and imides were described, which is divided into three main sections: (1) tertiary MCP amides, (2) MCP imides, and (3) secondary MCP amides. Depending on the MCP substrates, reactions with aldimines and aldehydes resulted in five different types of heterocyclic scaffolds such as pyrrolidines, furans, pyridinones, pyranones, and pyrrolones. A key intermediate was a binfunctional vinylogous enolate generated in situ from distal bond cleavage of monoactivated MCPs in the presence of MgI2. Hydrostannation using a new homogeneous palladium catalyst system has been described in Chapter III. Using this catalyst, a regioselective ring cleavage of MCP esters and ketones occurs yielding a tin enolate which further undergoes aldol reaction. In addition, hydrostannation of unactivated double bonds has been achieved.; In Chapter IV, the synthesis of an unsymmetrical acyclic N,N -acetal has been briefly studied focusing on the reaction between various acyl amido-based nitrogen nucleophiles and N-tosyl alkyl aldimines. |
