Development of New Methodology in Organic Synthesis: Lewis Acid-Mediated Rearrangements of Ammonium Ylides and Addition of 1, 3-bis(silyl) propenes to Aldehydes
Abstract: This thesis deals with the development of new methodologies in organicsynthesis. The main focus is on the development of Lewis acid-mediated [1,2]-rearrangements of ammonium ylides and the novel addition of 1,3-bis(silyl)propenes to carbonyl compounds.The first part of this thesis describes the development of a Lewis acidmediated[1,2]-Stevens rearrangement of various glycine derivatives. Thismethodology was then applied to the development of an asymmetric Lewisacid mediated [1,2]-Stevens rearrangement of cyclic ammonium ylides. Theremarkably high degree of C?N?C chirality transfer is described. Inaddition, this methodology was successfully applied to the synthesis of variousquaternary proline derivatives in enantiomerically pure form.Secondly, a brief study of the asymmetric [2,3]-rearrangement of ?-substitutedglycine derivatives is presented. The investigation revealed a severely limitedreaction scope. The subsequent study on developing super-reactive cationicLewis acid also met with little success.Finaly, an addition reaction of various 1,3-bis(silyl)propenes to glyoxalates hasbeen developed. The reaction products correspond to the direct vinylation ofglyoxalates. The corresponding highly functionalized ?-hydroxy allylsilaneswere obtained in high yields.
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