SYNTHETIC ORGANOSILICON CHEMISTRY

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We intend to carry out basic research in two important areas of synthetic organosilicon chemistry: the use of silacavitands for anion complexation and chirality transfer from silicon to carbon. Both of these areas have the potential for a major contribution to synthetic organic and medicinal chemistry. We propose to investigate the complexing ability of several polysilanes toward halogen atoms. In particular we plan to prepare molecules with three or four silicon atoms located at the vertices of molecular triangles and tetrahedra, respectively, compounds we call silacrowns and silacryptands. We plan to study the strength with which these silacryptands bind negatively charged atoms such as the halides and some polyatomic anions (carbonate, nitrate, phosphate). Should these silacryptands bind as strongly as we anticipate, they should open up an entire new field of study, namely the generation and reaction of unsolvated ("free" or "naked" metal ions, cations, and even protons in apolar organic solvents. The effect of these unsolvated electrophiles on important organic reactions, e.g., Diels-Alder reaction, aldol condensation, Friedel-Crafts reaction, etc., will be fully tested, with the potential for improving or altering the course of these reactions. In the second area, we propose to prepare chiral trialkylsilyl derivatives (silyl enol ethers, silyl nitriles, silyl hydrides, etc.) and investigate their reactions with prochiral molecules. We expect to see substantial chirality transfer from silicon to carbon, a process as yet not well demonstrated in organosilicon chemistry. In this way one would be able to prepare easily very large numbers of important organic molecules (e.g., sugars, macrolides, amino acids, etc.) in their correct optically pure forms by utilizing the chirality at silicon as the only source of asymmetry. This process, if successful, would be of great value to synthetic organic and medicinal chemistry.