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(2009) Weiner, Barbara
The research presented in this thesis had the objective to use enzymes and transition metal catalysts to find new and efficient methods for the synthesis of β-amino acids from cheap starting materials. β-Amino acids are key structural elements of peptides, peptidomimetics and other natural products. Consequently they are essential chiral building blocks for the synthesis of pharmaceuticals. In chapter 1, recent catalytic asymmetric methods for the synthesis of β-amino acids and derivatives are reported. Chapter 2 describes studies the use of the microbial enzyme aspartate ammonia lyase (AspB) from Bacillus sp. YM55-1 in conjugate addition reactions of ammonia to fumarate derivatives. This enzyme was used for the preparation of N-substituted aspartic acids with excellent enantioselectivities (>97%). In chapter 3, the use of the enzyme phenylalanine amino mutase (PAM) from Taxus chinensis is described for the addition of ammonia to cinnamic acid derivatives to synthesize α- and β-amino acids. In chapter 4, aldehyde selective Wacker oxidations of phthalimide protected allylic amines for a new route to β-amino acids are reported. The β-amino-aldehydes are formed in excellent yields (up to 94%), and the new oxidation method exhibits a large substrate scope. In chapter 5 attempts to perform a Curtius rearrangment of thioesters is reported. Chapter 6 describes the copper catalyzed asymmetric 1,4-addition of Grignard- and dialkyl zinc reagnents to activated α,β-unsaturated fumarate derivatives. To summarize, new catalytic methods were developed for the synthesis of β-amino acids using biocatalysis and transition metal catalysis.
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http://irs.ub.rug.nl/ppn/320485137 |
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